单选题 The organization has so far raised $2.5 million to finance bone ______trans- plants for children.
【正确答案】 A
【答案解析】[解析] marrow骨[精]髓，精华，实质；moron低能者，笨人；mussel贻贝，蚌类；mire泥潭，淤泥，泥浆。根据题意，A项为正确答案。