Read the following article and answer the question. Article: In Canada you can find dogs, cats, horses, etc. in almost every family. These are their pets. People love these pets and have them as their good friends. Before they keep them in their houses, they take them to animal hospitals to give them injections so that they won't carry disease. They have special animal food stores, though they can get animal food in almost every kind of store. Some people spend around two hundred Canadian dollars a month on animal food. When you visit people's houses, they would be very glad to show you their pets and they are very proud of them. You will also find that almost every family has a bird feeder( ) in their garden. All kinds of birds are welcomed to come and go and nobody animal in Canada. They have a law against an animal happened to get run over by a car, people would be very sad about it. Question: They give their pets injections before keeping them at their houses because _ . Answer:
Choices:
I. the pets are sick;
II. the pets are wild;
III. they want to stop them from carrying disease;
IV. they want them to sleep on the way home;
III.