Explanation:

Correct answer is (a). The hint word or the defining word here is the possessive adjective ‘her’. This occurs in the predicate part of the sentence (the part of a sentence or clause containing a verb and stating something about the subject) containing this possessive adjective hints at a subject that is singular in nature. In other words “representative is” will make the sentence grammatically more correct. Hence the option A) A great representative is, is the correct option.