(A) For every book if there exists a shorter book, then harshal has written the shorter one and amit the longer one.
(B) Every book written by Harshal is longer than every book written by Amit.
(C) There exists an x such that if x is a novel written by Harshal, then all novels written by Amit are shorter than x.
(D) There exists an x such that x is a novel written by Harshal and all novels written by Amit are shorter than x.
So, (D) is the answer