从方框中选择句子补全下面的对话。

A. Is that OK? B. Can I help you? C. That's cheap. D. How much is it?

Mom: Look at the skirt.

Lily: It's pretty.

Assistant:

Lily: Can I try on that skirt?

Assistant: Sure. Here you are.

Mom:

Lily: Yes. It's just right.

Mom:

Assistant: 30 yuan.

Mom: We'll take it.