Question

Which personal pronoun correctly completes the sentence?

Answer 1

A because if you put it at the beginning it makes perfect sense.

Answer 2

If you can change the wording and have it still make sense, you've found the answer. 
SHE is the newest candidate for city council.
HER is the newest candidate for city council.
HERS is the newest candidate for city council.
The answer is A because it's the only one that makes sense.