+ an-1' /2"-1. A The weight of a sequence ao, a, , an-1 of real numbers is defined as ao + a/2 + ... subsequence of a sequence is obtained by deleting some elements from the sequence, keeping the order of the remaining elements the same. Let X denote the maximum possible weight of a subsequence of ao, a,..., an-1 and the maximum possible weight of a subsequence of a, a2, ..., an-1. Then X is equal to A. max(Y, ao + Y) B. max(Y, ao+Y/2) C. max(Y, ao + 2X) D. ao + X/2