(A) It revealed that Mexico was getting ready to enter the war on the German side.
(B) ** It promised Mexico that Germany would help it reclaim territory in the United States if Mexico would go to war against the United States.
(C) Zimmerman was passing American secrets to Germany with the help of Mexican leaders
(D) The telegram contained secret messages sent by American leaders to its commanders on European battlefields
EXPLANATIONS BELOW
Concept note-1: -The message was sent to the German ambassador to Mexico, Heinrich von Eckardt . Zimmermann sent the telegram in anticipation of the resumption of unrestricted submarine warfare by Germany on February 1, which the German government presumed would almost certainly lead to war with the United States.
Concept note-2: -The note revealed a plan to renew unrestricted submarine warfare and to form an alliance with Mexico and Japan if the United States declared war on Germany. The message was intercepted by the British and passed on to the United States; its publication caused outrage and contributed to the U.S. entry into World War I.
Concept note-3: -In January 1917, British cryptographers deciphered a telegram from German Foreign Minister Arthur Zimmermann to the German Minister to Mexico, Heinrich von Eckhardt, offering United States territory to Mexico in return for joining the German cause.
Concept note-4: -This telegram, written by German Foreign Secretary Arthur Zimmermann, is a coded message sent to Mexico, proposing a military alliance against the United States.