The three correct statements that describe the United States' movement from neutrality to engagement in World War I are:
B. One of the main causes of the United States declaring war on Germany was the use of unrestricted submarine attacks.
C. President Wilson campaigned in the 1916 election with the slogan "He kept us out of war."
E. The United States began to support war against Germany after the Zimmerman telegram was intercepted.
Statements A and D are incorrect. The United States declared war on Germany in 1917, not 1916, after a series of events, including the sinking of the Lusitania and the Zimmerman telegram. Additionally, prior to the war, the United States had more trade and loans with Great Britain than with Germany.