Definition: You are given a question on human aging. You are also given 4 answer options (associated with "A", "B", "C", "D"), out of which only one is correct. You need to answer the question by selecting the correct option. You should only answer with the choice letter, not the whole answer.
Input: Loss of muscle fiber may be due to loss of neurons which may be due to
(A)Clogged blood vessels (B)Loss of bone density (C)Changes in hormone levels (D)Loss of collagen

A