The correct answer is (C).
Getting to the Answer: When a verb is underlined, check to make sure that it agrees with its subject. In this question, the subject "computer" is singular, so it requires a singular verb.
(A) Incorrect: "have" is plural verb, but "computer" requires a singular verb
(B) Incorrect: "are" is a plural verb, but "computer" requires a singular verb
(C) Correct: the singular verb "has" agrees with the singular subject "computer" and retains the sentence?s intended meaning
(D) Incorrect: while "is" is a singular verb, this choice changes the original meaning that the computer possesses "random-access memory"