Which of the following was a main cause of the unemployment trend seen in the line graph
a.)the united states lost trade after congress approved the neutrality
b.)millions of americans joined the u. s. military
c.)more and more women began working in factories
d.) trade between american and german companies skyrocketed

B) Millions of Americans joined the U.S. military

Explanation:

One of the reasons why the unemployment rate dramatically decreased during these years was because millions of Americans joined the U.S. military. This is because during these years, World War II was taking place. Although the United States had remained neutral during the first few years of the war, it decided to get involved after the Japanese attack on Pearl Harbor.

a peace conference held after the surrender of japan

an international conference held near the end of world war ii

a meeting of the victorious nations after the defeat of germany

a summit meeting between the united states and the soviet union