根据对话内容从方框中选择能填入空白处的最佳选项补全对话

A: Hi, Mum!

B: Yes, I can.

A:

B: At Tian' anmen Square.

A: Great.

B: I m walking around. There are lots of people here.

A: Oh, what is my father doing?

B:

A: Have a good time.

B: Thank you!

A: Bye!

A. He is buying some presents. B. What are you doing? C. Goodbye! D. Where are you? E. Can you hear me?