Which process group creates the contract change control system?

A.  Initiating
B.  Planning
C.  Executing
D.  Monitoring and Controlling 

I chose D: Monitoring and controlling.

But the answer it is showing is C: as executing process group.

I know the tool contract change control system is used under administer procurement process(Monitoring / controlling group process).

For that reason chose D as my answer. but the system is showing C: executing process group as the answer.