B

Policeman(男警察): Hello!

Marcus: Hello! I lost my bag(包)this morning．

Policeman: What color is your bag?

Marcus: It's black．

Policeman: We have two bags here．Is this your bag?

Marcus: No, it isn't.

Policeman: Is that your bag?

Marcus: Yes! That's my bag!

Policeman: What's in your bag?

Marcus: My keys, my book, my green pen ... Oh, and my white phone.

Policeman: What's your name?

Marcus: Mr. Smith.

Policeman: What's your first name，Mr. Smith?

Marcus: Marcus．

Policeman: Yes，it's your bag．Here you are．

Marcus: Thank you．

根据材料内容选择最佳答案。