单选题 Clark felt that his ______ in one of the most dramatic medical experiments of all time was worth the suffering he underwent.
[A] apprehension [B] appreciation [C] presentation [D] participation

【正确答案】 D
【答案解析】participate in参加，参与；apprehension领悟；appreciation欣赏；presentation呈现，提供。句意：克拉克感到他能参加目前为止最伟大的医学实验之一，所经历的那些痛苦是值得的。