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 :)
Answer: The US Senate
Explanation: Each state gets 2 representatives, so there is 100 members of the senate
The <span>availability of cheap books greatly advanced the spread of learning in the renaissance since it made knowledge available to the lower classes instead of only the elite--as had been the case in the past. </span>

Unrestricted submarine warfare is a type of naval warfare in which submarines sink vessels such as freighters and tankers without warning, as opposed to attacks per prize rules (also known as "cruiser rules").