Comprehensive and Detailed In-Depth Explanation:
Branch testing is a structural testing technique that ensures each branch (decision point) in the control flow is executed at least once. The goal is to measure branch coverage, which is the number of branches exercised divided by the total number of branches.
(A) describes statement testing, not branch testing.
(B) and (D) introduce confusion between decisions and statements, whereas branch testing focuses on control flow branches.
In simple terms, branch testing checks that all possible decision outcomes (true/false) are executed, whereas statement testing only ensures that each line of code is executed.

The question is about identifying an example of testing contributing to higher quality. Quality is the degree to which a component, system or process meets specified requirements and/or user/customer needs and expectations1. Testing is the process consisting of all lifecycle activities, both static and dynamic, concerned with planning, preparation and evaluation of software products and related work products to determine that they satisfy specified requirements, to demonstrate that they are fit for purpose and to detect defects2.
Therefore, testing contributes to higher quality by verifying and validating that the software products and related work products meet the specified requirements, are fit for purpose and have no defects, or at least have a reduced number of defects. Testing also provides information about the quality of the software products and related work products to the stakeholders, who can make informed decisions based on the test results3.
Out of the four given statements, only option D is an example of testing contributing to higher quality, as it shows that testing has detected a defect (a flaw in a component or system that can cause the component or system to fail to perform its required function4) and that the defect has been resolved (fixed and confirmed) prior to release (delivery of the software product to the customer or end user). This means that testing has prevented a potential failure (an event in which a component or system does not perform a required function within specified limits) from occurring in the operational environment, and thus has improved the quality of the software product.
Option A is not an example of testing contributing to higher quality, as it is a reporting activity that summarizes the test results and evaluates the test objectives, but does not directly affect the quality of the software product or related work products. A test summary report is a document that records and communicates the outcomes of testing activities, including test completion criteria, test results, incident reports, test summary and evaluation, and lessons learned.
Option B is not an example of testing contributing to higher quality, as it is a planning activity that estimates the resources and time needed for testing activities, but does not directly affect the quality of the software product or related work products. A test effort estimate is an approximation of the amount of work and/or the duration of time required to perform testing activities.
Option C is not an example of testing contributing to higher quality, as it is a preparation activity that sets up the test environment (an environment containing hardware, instrumentation, simulators, software tools, and other support elements needed to conduct a test), but does not directly affect the quality of the software product or related work products. A test environment installation is a process of installing and configuring the test environment according to the test environment specification.
Reference:
1: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 10
2: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 11
3: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 12
4: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 13
5: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 13
6: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 77
7: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 78
8: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 79
9: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 80
10: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 81
11: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 82
12: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 83
13: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 84
14: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 85
15: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 86
16: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 87
17: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 88
18: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 89
19: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 90
20: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 91
21: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 92
22: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 93
23: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 94
24: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 95
25: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 96
26: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 97
27: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 98
28: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 99
29: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 100
30: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 101
31: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 102
32: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 103
33: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 104
34: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 105
35: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 106
36: ISTQB Certified Tester Foundation Level Syllabus 2018, Version 4.0, p. 107

A defect is a flaw in a component or system that can cause the component or system to fail to perform its required function. A defect can cause harm to the end customer, the company, or both, depending on the impact and severity of the failure. In this case, the defect in the code causes the system to lock down accounts that have an overdraft higher than $1000, instead of $10,000. This can cause harm to the end customer, as they may lose access to their funds and face inconvenience or financial difficulties. This can also cause harm to the company, as they may lose customer trust and satisfaction, face legal issues or complaints, or incur additional costs for fixing the defect and restoring the accounts. Verified Reference: [A Study Guide to the ISTQBFoundation Level 2018 Syllabus - Springer], Chapter 1, page 3-4.

This answer is correct because product risks are risks that affect the quality of the software product, such as defects, failures, or non-compliance with requirements or standards. Project risks are risks that affect the project's schedule, budget, resources, or scope, such as delays, cost overruns, skill gaps, or scope changes. In this case, [I] and [IV] are product risks, as they relate to the accessibility and security of the software product, which are quality attributes. [II] and [III] are project risks, as they relate to the delivery time and the test automation skills of the test team, which are project factors. Reference: ISTQB Glossary of Testing Terms v4.0, ISTQB Foundation Level Syllabus v4.0, Section 2.1.1.1