Which sentence uses a verb that agrees with its subject? a. is the potato chips stale? b. has the scuba divers from the boat surfaced yet? c. were they picking the paint color for the bathroom? d. does she and her aunt plan to go swimming at the pool?

A: is incorrect because the sentence is talking about more than one potato chip, so it should be Are the potato chips stale? 
B: Is incorrect because it is talking about more than one scuba diver. So it should be Have the scuba divers from the boat surfaced yet?
C: Is Correct.
D: Is incorrect because you are suppose to use Do instead of Does.