Answer:
The correct answer to the question: Which option best completes the diagram, would be: B: Migration to the Sun Belt.
Explanation:
After World War II, there were several circumstances that brought economic revival, and moreover, growth, in the United States. One of them, was the baby boom, which encouraged people to seek other places to live, larger spaces, outside of cities, and to seek homes in the suburbs. There was also an enlargement of existing companies, agricultural development, and enlargement of the workforce with the return of the soldiers who had gone to the war. But probably one of the biggest boosters for the American economy, was the huge migration that started happening around the 50´s, and beyond, towards the Sun Belt, and thus generating a growth of the cities in this region. An example of this was California, who, by 1963, had many more people living in it than New Yor. This caused an economic development of cities that had previously lagged behind those in the East coast, and thus brought even more opportunities for businesses to grow.