Which of the following is a pattern in the American family

As the options for the question are not mentioned, lets discuss the general pattern of an American family.

On an average, an American family will mostly contain 3 people. The pattern of living is a nuclear family style. A nuclear family means the mother, father ans the children living together. However, there are some minorities in America where grandparents also live in the family and their are other families consisting on only a single parent. However, the wide majority is of a nuclear family.