B.
The US never declared war on Germany because of the Poland invasion. Britain and France declared war on Germany because of the Poland invasion.
The United States was having the most problems with Japan, and the US declared war on Japan shortly after they bombed Pearl Harbor.
Once the US declared war on Japan, Germany declared war on the US due to the Tripartite Pact.
Well, they wanted religious freedom and separation from the church of England. As well, America brought forth new opportunity, and new potential growth of an stable settlement which would soon turn into a city, than which would forth bring up a nation.
Active military intervention