Read the sentence to find out whether there is any error in it or not. The error, if any, will be in one part of the sentence. The number of that part (which has the error) is the answer. If there is no error, the answer is (5). Ignore errors of punctuation, if any.

One of the major difficulties (A)/ with optimization methods arises (B)/ in the first step is that of specifying (C)/ the fitness quantity to be maximize. (D)