If A, then B.
If B, then C.
If C, then D.
If all of the statements above are true, which of the following must also be true?


(A) If D, then A.
(B) If not B, then not C.
(C) If not D, then not A.
(D) If D, then E.(C)
(E) If not A, then not D.

what could be the answer ??