(A) German U-boats were ordered to sink US vessels
(B) Kaiser Wilhelm proposed a plan for the invasion of England
(C) Archduke Ferdinand proposed a treaty to President Wilson
(D) ** Germany proposed an alliance with Mexico against the US
EXPLANATIONS BELOW
Concept note-1: -The Zimmermann 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.
Concept note-2: -The answer was simple: land. During the era of American expansion, Mexico lost the lands that are today Texas, New Mexico, and Arizona. Germany help would allow Mexico to take back what they had lost.
Concept note-3: -Zimmermann’s alliance proposal did reach the desk of Mexican President Carranza, but it was officially rejected once a military commission determined that there would be no benefit in accepting it.