Answer:
A. the construction of raised fields along rivers
Explanation:
They provided financial support to young artists and writers in there time.
Baby boom fits that description.
The US never wanted to join World War II so they isolated themselves from everything that was going on and tried to stay neutral (Over time, we sided with the Allies). Mainly, we entered due to the Japanese attack on Pearl Harbor. After the bombing, the US decided to declare war on Japan. Soon after, Nazi Germany's leader declared war on the US and then the US was officially in the war.
So, all in all, it was the bombing of Pearl Harbor on December 7, 1941.
Hope this helps :)
