<p>Strange question.</p>
<p>A is conspicuously wrong but C looks bad as well. It looks like a verb is missing or a semicolon and a verb.
Anyway, I would always choose A, because I’m very sure that a subject in the form “a, b and c” cannot go with a singular verb.
Regarding C, it might only be some grammatically-correct, fancy style the SAT-writers might want to throw.</p>