Which of the following is considered a primary social factor influencing the long-term decline in birth rates in modern societies?

Match the factors with their primary sociological or demographic role in the demographic transition process: 1. Female literacy — a. Slower child mortality and overall death rate decline2. Vaccination programs — b. Significant modern decline in birth rate and fertility3. Urbanisation — c. Transition to smaller families and workforce changes4. Economic prosperity — d. Delaying the average age of marriage Which of the following aligns best with standard demographic effects?