This is not a nice question. On the surface, it looks like C and D are both correct.
Coming back to the starting point makes the displacement = 0. That means that the velocity is also 0.
On the other hand, the total displacement when going in a circle can also be zero.
To me the best answer is probably D, but I wouldn't be surprised if the poser of the question thinks it is C. I would answer D but hold your nose when you do it.
It's going to differ between people. Some people will have trouble staying focused on the prompt. Others will find difficulty in supporting their ideas. Still others may be unable to utilize grammar effectively.
