单选题 .  For most people, life is easier and more comfortable than ever before. Convenient foods from the supermarket simplify shopping and cooking. Household appliances like the vacuum cleaner and the washing machine have taken the drudgery out of housework. Released from these household chores, many wives have found jobs outside the home. Women are achieving economic independence.
    Families, too, are simpler today. In America, it is not customary for parents to live with their married children. With our greater mobility, relatives have scattered, the parents retiring to Florida or Arizona and the young people, after they marry, going wherever their jobs or their parents or their interests take them.
    Young adult women have new freedom, too. While attending college, they often live away from home, sometimes far from their parents or their relatives. After college, they move to the city, find a job, and set up a bachelor apartment. This is the era of women's liberation.
    But all this freedom and affluence (富裕) have had an unforeseen and in some aspects a devastating (破坏的) effect on marriage.1.  In the US, families are becoming ______.