"The lecturer was a tall thin man with white hair." "Then it _______Dr.Fell because h【单选题】

"The lecturer was a tall thin man with white hair." "Then it _______Dr.Fell because he is short and fat.It_____Dr.Jones;he is thin."

A. can't be/must be

B. mightn't have been/could have been

C. must be/can't be

D. can't have been/must have been