Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions.

One of the best ways to learn about different kinds of habitats is to go to your local zoo. Zoos are usually set up by habitat. African animals are often together. Elephants, zebras, lions, rhinoceroses and monkeys are in the same habitat. Australian animals, such as koalas, kangaroos, platypuses and emus are kept in another section. Some parts of the zoo keep animals in indoor habitats. It is easier to control the temperature in indoor habitats. This keeps the animals from getting too hot or too cold. Snakes and reptiles are kept in indoor habitats. Penguins are often kept inside as well. Birds are kept in aviaries. Aviaries are large enclosed spaces that seem like the birds' natural environment. Aviaries keep birds from escaping and keep other animals away from them.

Zookeepers are people that work at zoos. They have studied animals and know how to care for them. Zoos often have animals that are sick. Zookeepers work to make the animals better. Zoos also keep animals that are endangered. There are many programs that breed endangered animals. Zookeepers help the animals transition to life in their natural environments. Then they let them back into the wild. A visit to the zoo teaches people a lot about animals and their habitats.

Zoos are usually structured ___________________.