Which best completes the sentence? If something can respond to a stimulus then it

A. is a living thing.

B. might be a living thing.

C. is not a living thing.

The answer is A

Because if something responds to a stimulus, it cannot be dead because that isn't logically possible and it can't be might because there is no possibility of it not being a live and only living things respond to stimulus and that is the only answer left that can and is correct.