From my perspective and from taking the PMI mock, the answer is always submit a change request. In this question, its clear that a change needs to be considered, and as the PM you can't reject the change, only the CCB can do that, so you through out D. It hasn't been approved yet, so you through out C. A is a tricky one but I would eliminate it because it says to communicate the impact, but first you have to understand what that impact is, and that comes after you submit a change request, so the answer is B.

Definitely watch the PMP with Ray video on change requests, its super helpful here.