阅读下面短文，然后从各题所给的四个选项中选出一个最佳答案。

There is a zoo in our city. My parents often take me there at1. I like animals. I have a 2 of toy animals in my room. In the3, I can see tigers, elephants, bears, monkeys, pandas, snakes, and many other4. Some animals are friendly, but some are not. Tigers, bears and some snakes are5. That is 6they have to stay in cages (笼子). But I do not think it is good for animals to stay in cages. They should be free. The animals in cages can't be7.

I think the most interesting animals in the zoo are the dolphins. I like watching them swim and jump. They swim so fast and jump so high. They can play 8a ball. They can stand up and walk in the water! They are very9to people. If you fall into the water and can't10, they may come to help you.