The United States entered World War I in April of 1917 only after Germany resumed submarine warfare against its ships in the Atlantic and a. after the discovery of a plot to assassinate President Woodrow Wilson. b. after bombardment of New York by German submarines. c. major riots broke out in all of America's principal cities. d. after discovery of the Zimmermann Telegram.

d. after discovery of the Zimmermann Telegram.

Explanation:

President Woodrow Wilson appeared before a joint session of Congress on the 2nd of April, 1917 to formally request a declaration of war against Germany.

The United States of America entered World War I (WWI) on the 6th of April, 1917 with its allies (Russia, France and Britain), only after Germany resumed an unrestricted submarine warfare against its passenger and merchant ships in the Atlantic and after discovery of the Zimmermann Telegram.

Zimmermann Telegram was a coded or secret diplomatic message sent on the 16th of January, 1917 from the German foreign office by secretary Arthur Zimmermann to the German minister in Mexico requesting for an alliance should the United States of America enter WWI against Germany.

not sure but thinking i'ts cause the government was broke. not sure