单项选择题

The greatest recent social changes have been in the lives of women. During the 20th century there has been a remarkable shortening of the proportion of a woman’s life spent in caring for children. A woman marrying at the end of the 19th century would probably have been in her middle 20s, and would be likely to have seven or eight children, of whom four or five lived till they were five years old. By the time the youngest was 15, the mother would have been in her early 50s and would expect to live a further 20 years, during which custom, opportunity and health made it unusual for her to get paid-work. Today women marry younger and have fewer children. Usually a woman’s youngest child will be 15 when she is 45 and can be expected to live another 35 years and is likely to take paid-work until retirement at 60. Even while she has the care of children, her work is lightened by household appliances and convenience foods.
This important change in women’s life-pattern has only recently begun to have its full effect on women’s economic position. Even a few years ago most girls left school at the first opportunity, and most of them took a full-time job. However, when they married, they usually left work at once and never returned to it. Today the school-leaving age is 16, many girls stay at school after that age, and though women tend to marry younger, more married women stay at work at least until shortly before their first child is born. Very many more afterwards return to full or part-time work. Such changes have led to a new relation in marriage, with the husband accepting a greater share of the duties and satisfactions of family life, and with both husband and wife sharing more equally in providing the money, and running the home, according to the abilities and interests of each of them.

One reason why the woman of today may take a job is that she （）.

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