The project manager develops a process improvement plan to encourage continuous process improvement during the life of the project.

My answer is "B": Process analysis

My choice is answer "A" Change Control System 

B. Process analysis, is the correct answer

I am little confused, and my answer is none of the above.  (which is not the option)

Change control system is to document change, may also address output of process. I think this is the closest one.

If I am allowed to add option there, I would say;

Either process validation or post implementation survey.

Process analysis, but I'd say that partly all techniques are important

The Process Improvement Plan documents the steps for analyzing processes with the purpose of improving the process. You should consider things such as process boundaries, process configuration, process metrics and targets for improved performance. 

I guess A. Change control system

The correct answer is

B. Process analysis.

Answer D, but answer C benchmarking is also a tool but harder to use during a Project, because the specific project details make benchmarking hard, but for certain processes possible

 I agree the optopn C

Benchmarking:

B Process Analysis  with checks and balances while the project is in process