Control Costs / Reserve Analysis

Hello Guys,
Question, in PMBOK it mentions, in Control Costs

- Ensure all change requests are acted in timely manner

I am confused, are you not tracking the status of change in Monitor & Control Project work?

in the exam if it asks where do you track the status of approved changes, is the the answer M&C project work or Control Cost?

Also you do Reserve analysis number of times, but the time you actually release the contingency funds for risks that can no longer happen is in Control Risk ?