Answer:
Option A, The industrial Revolution
Step-by-step explanation:
During the early 90s, an economically stable family structure was the close knit family structure in which the husbands were the bread earner and the mother used to take care of home and children. But with the rise of Industrial revolution, women too started working and by 1960s, one third of the women were employed either on full time role or part time jobs. This led to diversification of American families into smaller, less stable and more diverse families.
Hence, option A is correct