What is a possible reason for the scheduler to not execute the application-specific activity?

A job scheduler with a NotifyBusinessUser activity has been created in an application to send emails every day. However, the scheduler processing is not working as expected. After thorough analysis, the production support team noticed that some other application-specific activity with the same name as NotifyBusinessUser is executed at runtime.

What is a possible reason for the scheduler to not execute the application-specific activity? (Choose two)
A . A sync requestor type rule does not have an application-specific access group.
B . An activity rule is marked as blocked in the highest version of the current application.
C . An activity rule is marked as blocked in the highest version of the current application.
D . The system runtime context does not include the application.

Answer: CD