See solution below.
Explanation:
Set up staging environments in Azure App Service
1. Open Microsoft Azure Portal
2. Log into your Azure account, select your app's resource page, in the left pane, selectDeployment slots > Add Slot.

3. In the Add a slot dialog box, give the slot a name, and select whether to clone an app configuration from another deployment slot. Select Add to continue.

4. After the slot is added, select Close to close the dialogbox. The new slot is now shown on the Deployment slots page. By default, Traffic % is set to 0 for the new slot, with all customer traffic routed to the production slot.
5. Select the new deployment slot to open that slot's resource page.

6. Change TRAFFIC % to 10
References:
https://docs.microsoft.com/en-us/azure/app-service/deploy-staging-slots

In some cases, you need to bypass policy requirements so you can push changes to the branch directlyor complete a pull request even if branch policies are not satisfied. For these situations, grant the desired permission from the previous list to a user or group. You can scope this permission to an entire project, a repo, or a single branch. Manage thispermission along the with other Git permissions.
References:https://docs.microsoft.com/en-us/azure/devops/repos/git/branch-policies

Explanation:

Box 1: RBAC
Management plane access control uses RBAC.
The management plane consists of operations that affect the key vault itself, such as:
Creating or deleting a key vault.
Getting a list of vaults in a subscription.
Retrieving Key Vault properties (such as SKU and tags).
Setting Key Vault access policies that control user and application access to keys and secrets.
Box 2: RBAC
References:
https://docs.microsoft.com/en-us/azure/azure-resource-manager/resource-manager-tutorial-use-key-vault

The Azure Pipelinespool provides all Azure DevOps organizations with cloud-hosted build agents and free build minutes each month. If you need more Microsoft-hosted build resources, or need to run more jobs in parallel, then you can either:
Host your own agents on infrastructure that you manage.
Buy additional parallel jobs.
Reference:
https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/pools-queues

Explanation:

Step 1: Create a dependency graph for the application
By linking work items and other objects, you can track related work, dependencies, and changes made over time. All links are defined with a specific link type. For example, you can use Parent/Child links to link work items to support a hierarchical tree structure. Whereas, the Commit and Branch link types support links between work items and commits and branches, respectively.
Step 2: Group the related components.
Packages enable you to share code across your organization: you can compose a large product, develop multiple products based on a common shared framework, or create and share reusable components and libraries.
Step 3: Assign ownership to each component graph
References:
https://docs.microsoft.com/en-us/azure/devops/boards/queries/link-work-items-support-traceability?
view=azure-devops&tabs=new-web-form
https://docs.microsoft.com/en-us/visualstudio/releasenotes/tfs2017-relnotes