听对话或独白，根据对话或独白的内容，从下面各题所给的A、B、C三个选项中选择最佳选项。每段对话或独白你将听两遍。
What’s the price of walking dogs for half an hour?
A. $2.            B. $4.            C. $10.
What are they mainly talking about?
A. How to walk dogs.
B. How to make money.
C. How to make advertisements.