正确答案是 A.can
How can it be = 怎么能够,为什么,何故?
Mr bush is on time for everything.How can it be that he was late for the meeting?
布什先生惯常是准时的.这一次的会议他怎么迟到了?为什么不能用should呢？这次他"竟然"迟到了How should it be that 不是 “为何他竟然迟到了” 的意思，How should it be that = 应该如何？要如何做？四个选项里只有 A 适合。只有 How can it be 符合问题的语境。