单选题 If a thing is conspicuous by its absence, it is something that everyone expects to be there.
【正确答案】 A
【答案解析】conspicuous意为“明显的，受注意的”，A项noticeable是其同义词，故A为正确答案。B、C、D三项分别意为“必要的”、“可惜的”、“漠不关心的”，均与句意不合。