Final answer:
The reduction in the opportunity cost of a woman's time is the answer most likely to reduce the birthrate, due to the correlation between increased economic opportunities for women and lower birth rates.
Step-by-step explanation:
The option most likely to reduce the birthrate is (d) a reduction in the opportunity cost of a woman's time.
Several factors influence birth rates, but focusing on the economic aspect, increasing opportunity costs for women has shown a correlation with reduced birth rates. Opportunity cost refers to the benefits a person could have received by taking an alternative action. When women have higher incomes and more educational and economic opportunities, the time spent on child-rearing represents a greater sacrifice in terms of lost income and personal advancement.
Consequently, as women gain more employment opportunities and their time becomes more valuable, they tend to have fewer children. This phenomenon is reinforced by economic research indicating that as the earnings potential for women rises, so does the cost of childbearing, leading to a decline in birth rates. Additionally, education, particularly for girls, is a strong factor in birthrate reduction. With additional schooling, women are empowered and tend to delay childbirth and have fewer children overall, thereby investing more in the socioeconomic growth of their communities.