F: Is that your dog? He has been digging up my flowers and chasing my cat. ,M: It's my dog, but you must be mistaken. We keep him in the house all the time, except when we walk him in the park. There must be another dog that looks like him.
(A) F: Sorry. It must be another cat looks like yours. (B) F: Just a minute! I do not quite follow what you are saying, would you mind repeating that? (C) F: Sorry. I must have mistaken it for your dog. (D) F: Sorry. I must have mistaken the dog that bit me for yours.
C