My friend, Victor, is a zoo keeper in the National Zoo. His work is very interesting but it is hard. Sometimes it is dangerous, too. Every morning the zoo keepers have to get up at five to prepare the food for the animals. Each kind of animal is given special food. For example, the lions must be given meat; the deer must be given grass and leaves; and the parrots must be given fruit and nuts. Sometimes some animals won't let the others eat their food. If this happens,  each of them must be fed separately (分离地).

    Every morning each cage must be washed by the zoo keepers. This can be dangerous, especially with lions and tigers. To make the work easier, the animals are locked in the sleeping compartments (隔间) while the cages are being washed. When the animals are sick, the zoo keepers must look after them. Each sick animal is kept in a separate cage and given medicine. Sometimes they must be given injections. It is not easy to inject a sick lion!

    All the keepers live near the zoo. Each of them has a small house. There he lives with his family. They do not have holidays on Sundays and public holidays. Instead, each of them has a day off during the week. Each keeper has a holiday on a different day from that of the other keepers.

    The most important job of the keepers is to look after the safety of the visitors. People must be prevented from doing dangerous things. Many people have been injured because they did careless things, like putting their hands into the lion's cage.

根据以上短文内容，然后从每题所给的四个选项中选择最佳选项。