My kitten got lost again yesterday.I ______ never have let it go

My kitten got lost again yesterday.I ______ never have let it go by itself.
A、might
B、should
C、would
D、could
【正确答案】：B
【题目解析】：根据句意，这里表示本不应做但却做了，用should have done形式。答案为B。