What was the Zimmerman Telegram?

Aa telegram sent by Germany to Woodrow Wilson declaring war against the United States
Ba telegram sent by an American diplomat pledging United States loyalty to the British Prime Minister
Ca telegram sent by an American diplomat to a Mexican foreign minister assuring Mexico of the United States neutrality
Da telegram sent by a German foreign minister to Mexico encouraging the nation to go to war against the United States if the United States declared war against Germany

Verified Answer :

The Zimmerman Telegram was "D. a telegram sent by a German foreign minister to Mexico encouraging the nation to go to war against the United States if the United States declared war against Germany," since Germany was increasingly worried that the US would join the war and fight against Germany. 

Answer:

D. a telegram sent by a German foreign minister to Mexico encouraging the nation to go to war against the United States if the United States declared war against Germany

Explanation:

Germany was increasingly worried that the US would join the war and fight against Germany.

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