I'd be careful here. You only have to submit a change request if the document is approved, baselined and under configuration management. I had an ACTUAL PMP exam question that described a situation in which the schedule was approved and baselined but NOT under configuration management. You only needed to get approval to change from the functional manager over scheduling.
That being said I would think FAST TRACKING would probably require a change request IF said activity exceeded a threshold in the schedule management plan (and was previously baselined and under configuration management). Cost baseline may or may not be affected since new resources aren't being used.
On the flip side, CRASHING would probably not affect the schedule, but would affect the cost baseline (since we are adding more people). Again, if it exceeds your planned threshold and baselined/approved and under configuration management, you need to issue a change request.
Your projects will naturally trend above and below the PMB due to funding limits and certain activities may take longer or less time and we won't issue a change request otherwise we will always be on schedule and cost because we would be adjusting both throughout the project, which negates any PM metric tracking. It's like running a race, but having the finish line move towards us!
So, long story short, as I recall from my exam the CR answer was often a trap answer and other answers were often better. A CR is corrective action, but the PMP exam likes problem solving and communication before inputting a CR, in my humble opinion.
Best advice, read the question and understand the context.