Final answer:
The period following World War II marked by a significant increase in birthrates is known as the 'baby boom,' which led to the creation of the baby boomer generation. The correct answer is a. Baby boom.
Step-by-step explanation:
Following the end of World War II, many parents wanted to have children as soon as possible, which resulted in a significant increase in birthrates. This period is known as the postwar baby boom. It began with the return of military personnel, the desire of young Americans to start families, and the economic stability that allowed established couples to have more children. This unprecedented population explosion occurred between 1946 and 1964, at which point in 1957, for example, an infant was born every seven minutes in America.
The postwar baby boom led to the creation of what's now referred to as the baby boomer generation, which gave shape to many societal and economic trends in the following decades. This era was marked by a sense of optimism and economic growth, resulting in a significant impact on the marketplace, as this generation wielded considerable consumer power. Therefore, the correct answer to the question is a. Baby boom.