这个是虚拟语气It's (high)time sb. should do sth.(其中should 不能省略) 故A不正确It's time sb. did sth. 由此判断B和C中有一个,did在此为省略句,用DID指代了感谢这件事。(自己理解,仅供参考)It's time for sb. to do sth.It's time for Sth.
B it's (high)sb. did sth.表示是某人该做某事的时候了