What act by Germany ( to Mexico) forced U. S to declare war on Germany in 1917

The Zimmerman Telegram (or Zimmermann Note or Zimmerman Cable) was a secret diplomatic communication issued from the German Foreign Office in January 1917 that proposed a military alliance between Germany and Mexico if the United States entered World War I against Germany. ;)

Explanation:

a plantation economy is an economy based on agricultural mass production, usually of a few commodity crops grown on large farms called plantations. plantation economies rely on the export of cash crops as a source of income.

i hope this : )