阅读下面短文，从短文后各题所给的A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
A
It looks like there are more cats around us today. In fact, now there are about 58.1million pet cats in China. China has the second largest number of cat owners in the world 1 the United States. Every year, more young people take cats as pets.
More cats bring more 2. Many people now work at pet shops and animal hospitals. But cats can become 3, too. Some people throw their pet cats away. Then the cats become 4. They can pass on diseases（疾病）, and they kill other animals like birds and frogs.
So in Japan and Australia, the governments 5 homeless cats to animal hospitals. Doctors operate on them. So the cats can't have babies. In this way, the number of cats will not go up.
