B. Read the passage carefully, then choose the correct answer.

The nuclear family, consisting of a mother, father, and their children, may be more an

American ideal than an American reality. Of course, the so-called traditional American

family was always more varied than we had been led to believe, reflecting the very different

racial, ethnic, class, and religious customs among different American groups.

The most recent government statistics reveal that only about one third of all current

American families fit the traditional mold and another third consists of married couples who

either have no children or have none still living at home. Of the final one third, about 20

percent of the total number of American households are single people, usually women over

sixty-five years of age. A small percentage, about 3 percent of the total, consists of unmarried people who choose to live together; and the rest, about 7 percent are single, usually divorced parents, with at least one child. Today, these varied family types are typical, and therefore, normal. Apparently, many Americans are achieving supportive relationships in family forms

other than the traditional one.

With what topic is the passage mainly concerned?