问题

I left my handbag on the train, but luckily someone gave it to a railway official.—How unbelievable to get it back! I mean, someone ________ it.(2011·江苏)
A:will have stolen
B:might have stolen
C:should have stolen
D:must have stolen
B:might have stolen
C:should have stolen
D:must have stolen
正确答案是: