Which of these caused the United States to become involved in World War I?
a. the German invasion of Poland Eliminate
b. repeated violation of treaties by Japan
c. enemy bombing of American military bases
d. threats to American security made by Germany
The correct answer is: d. threats to American security made by Germany
Specifically, the threats were about Germany trying to make Mexico wage war on the US and Germany attacking submarines in the Atlantic, which was against international treaties.
