What led the U. S. to join the fighting?

The British gave President Wilson the Zimmerman telegram on February 24, and on March 1 the U.S. press reported on its existence. The American public was outraged by the news of the Zimmerman telegram and it, along with Germany's resumption of submarine attacks, helped lead to the U.S. to join the war.

if i am correct the answer is going to be a) the federal program of reconstruction ended.

the answer is c. they believed the royal family should hold all the power.