Answer:
D. On average married younger and had more children.
Step-by-step explanation:
The birth rates in US increased after the second world war. More than 4 million babies were added to the US population each year between 1946 and 1964. The main reason for it was the strong postwar economy that helped them to be confident to have a large number of children. Today most of the baby boomers are near the age of retirement. The soldiers rushing back to their homes and getting married to start a family before they were called for duty, the extra pay the soldiers received due to having family was also one of the major contributors.