从所给出的句子中选出合适的选项完成对话。

A. We should plant more trees. B. What makes the air dirty? C. Why is there dust? D. Where is the smoke from? E. Good for you!

Miss Fang: Hi, Children!

Kitty: The smoke and the dust (灰尘) make the air dirty.

Miss Fang: Good!

Ben: It's from the cars, buses and the factory.

Miss Fang: Great!

Peter: Because people cut down a lot of trees. The wind blows strongly and there is dust everywhere.

Miss Fang: What should we do to keep the air clean?

Alice:

Miss Fang: Great!