this question needs more support in order to be answered.
Answer:
D. Manifest Destiny.
Explanation:
The idea that the U.S. was meant to expand into new territories was known as Manifest Destiny.
This was very important during Westward Expansion and at the end of the 1800s, many Americans thought the U.S. should continue to expand, even overseas.
The baby boom affected the economy in a positive way. People moved to the suburbs, and the housing market was in a good position.
The Baby Boom created a demand for....
day care
teachers
bigger cars
bigger houses
nurses/doctors
more clothes
more electronics
more necessities for babies
more consumers
Hope this helps!