Nilisimama ili nivute sigara = I stopped (moving) (in order) to smoke.
Niliacha kuvuta sigara = I stopped/quit smoking.
This is why giving us single words as exercises is useless!
I get kusimama as "to stand (still), stop, be stationary, and kuacha as "quit, stop, cease".
So who knows? If you think your answer is a valid translation given what you have to work with, report it next time the sentence comes up. Worst that could happen is it doesn't get accepted.