The subject of my study is women who are initiating social change in a small region in Texas. The women are Mexican Americans who are, or were, migrant agricultural workers. There is more than one kind of innovation at work in the region, of course, but I have chosen to focus on three related patterns of family behavior.
The pattern I life style. represents how migrant farm workers of all nationalities lived in the past and how many continue to live. I treat this pattern as a baseline with which to compare the changes represented by pattern Ⅱ and Ⅲ. Families in pattern I work and travel in extended kin units, with the eldest male occupying the position of authority. Families are large and no children are unusual. And all members are economic contributors in this strategy of family migration. Families in pattern Ⅱ manifest some differences in behavior. while still maintaining aspects of pattern I. They continue to migrate but on a reduced scale, often modifying their schedules of migration to allow children to finish the school year. Parents in this pattern often find temporary local jobs as checkers to make up for lost farming income. Pattern Ⅱ families usually have fewer children than do pattern I families.
The greatest amount of change from pattern I, however, is in pattern III families, who no longer migrate at all. Both parents work full time in the area and have an average of three children. Children attend school for the entire year. In pattern Ⅲ, the women in particular create new roles for them selves for which no local models exist. They not only work full time but may, in addition, return to school. They also assume a greater responsibility in family decisions than do women in the other pat terns. Although these women are in the minority among residents of the region, they serve as role models for others, causing moderate changes to spread in their communities.
Now opportunities have continued to be determined by pre-existing values. When federal jobs became available in the region, most involved working under the direction of female professionals such as teachers or nurses. Such positions were unaccepted to many men in the area because they were not accustomed to being subordinate to women. Women therefore took the jobs, at first, be cause the income was desperately needed. But some of the women decided to stay at their jobs, at first, after the family' s distress was over. These women enjoyed their work, its responsibility, and the companionship of fellow women workers. The steady, relatively high income allowed their families to stop migrating. And, as the benefits to these women became increasingly apparent, they and their families became even more willing to consider changes in their lives that they would not have considered before.
Which of the following titles best reflects the main focus of the passage？

A Survey of Three Mexican American Families at Work in Texas.
B. Innovative Career Women: Effects on Family Unity.
Changes in the Life Styles of Migrant Mexican American Families.
D. Farming of Family: The Unavoidable Choice for Migrant Farm Workers.