Explanation
Graphical user interface, text, application, email Description automatically generated

Box 1: "autoInvokeaction"{
With the autoInvokeAction property on actionable messages, you can provide an HTTP endpoint to retrieve an up-to-date Adaptive Card payload with the latest information when the user opens the email in Outlook.
Box 2: "method": ";POST",
With the autoInvokeAction property on actionable messages, you can provide an HTTP endpoint to retrieve an up-to-date Adaptive Card payload with the latest information when the user opens the email in Outlook.
Reference:
https://docs.microsoft.com/en-us/outlook/actionable-messages/auto-invoke

Explanation

Explanation
Group writeback in Azure AD Connect synchronizes Office 365 groups only from Azure Active Directory back to the on-premise Active Directory.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-preview

Explanation
Graphical user interface, text, application, chat or text message Description automatically generated

Reference:
https://docs.microsoft.com/en-us/power-platform/admin/environments-overview

Explanation

Box 1: 2
You don't need to verify Sub1.contoso.onmicrosoft.com because the onmicrosoft.com domain and DNS is managed by Microsoft. You also don't need to configure an MX record for Sub1.contoso.onmicrosoft.com because that will be done by Microsoft.
For sub2.contoso.com, you don't need to verify the domain because you have already verified its parent domain contoso.com. However, you do need an MX record to direct email for that domain to Exchange Online.
For Fabrikam.com, you will need to verify the domain. You will need an MX record to direct email for that domain to Exchange Online.
Box 2: 0
You 'should' create CNAME records for autodiscover to point your email clients to Exchange Online to connect to the mailboxes. However, you don't have to. You could configure the email client manually.
Therefore, the minimum number of CNAME records required is zero.