Which type of execution mode is in use?

You need to identify the execution mode that is being used for the ISV solution reported by User5.

Which type of execution mode is in use?
A . asynchronous
B . atomicity
C . transfer
D . synchronous

Answer: D

Explanation:

User5 receives the error message: ‘Endpoint unavailable’ during a test of the technician dispatch ISV solution.

When you choose to use a synchronous execution mode any failure will be reported back to the user of the application with an Endpoint unavailable error dialog informing the user that the webhook service endpoint may be configured incorrectly or is not available.

Reference: https://docs.microsoft.com/en-us/powerapps/developer/common-data-service/use-webhooks