根据对话内容，从对话后的选项中选出能填入空白处的最佳选项。

A. Yes, it is. B. I'm fine. C. How are you? D. You are welcome. E. .How do you spell it?

Mike: Good morning, Tom,  

Tom: I'm OK, thank you. And you?

Mike: Is this your pencil?

Tom: It's my pencil.

Mike:

Tom: P-E-N-C-I-L.

Mike: Oh, I see. Thank you.

Tom: