Choose the sentence that is correct without adding a comma.（）

Choose the sentence that is correct without adding a comma.（）
A.He left the scene of the accident and tried to forget that it had happeneD.B.He replied "I have no idea what you mean."
C.After a good washing and grooming the pup looked like a new dog.
D.Vests which were once popular have been out of vogue for several years.
正确答案：He left the scene of the accident and tried to forget that it had happened.