You need to receive an e-mail notification if WF1 is postponed

You create a workflow named WF1. WF1 is attached to a list named List1. You need to receive an
e-mail notification if WF1 is postponed. What should you do?

A.
Use a HandleExternalEvent activity in WF1.

B.
Attach an SPWorkflowEventReceiver event receiver to List1.

C.
Attach an SPItemEventReceiver event receiver to List1.

D.
Use a ReceiveActivity activity in WF1.