Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 31 to 35.

     In many modern countries, people think of a family as a mother, a father and their children. But this is not the only kind of the family group. In some parts of the world, a family group has many other members. This kind of large family is called an "extended family" or a "joint family".  

     The joint family includes all living relatives on either the mother's or the father's side of the family. It is made up of grandparents, parents, brothers, sisters, uncles, aunts, and cousins. They live together in a large house or in huts built close together.

     Early people probably lived in joint families. They had to be part of a large group in order to survive. The members of the group helped each other hunt. They worked together to protect themselves from dangerous animals and other enemies.

     In China, people lived in joint families. When a son married, he and his 'wife lived at his parents' home. Unmarried daughters remained at home until they married. Chinese children felt very loyal to their parents. Younger members of the joint families always took care of the old ones.

     In India and Africa, some people still live in joint families. The members of a joint family share their earnings and property. If one member of the group becomes ill or has bad luck, the others help the person. As in the past, the members of the joint family offer each other help and protection.

What is the main idea of the passage?