The most likely direct result of the telegram would have been the prolongation of the war in Europe, not the end of it. So the answer is C.
The most direct result of the Zimmermann Telegram was A. The end of U.S. isolationism.
Here’s why:
The telegram, intercepted and revealed by the British, exposed Germany’s attempt to incite Mexico against the U.S.
This act of aggression, along with Germany’s unrestricted submarine warfare targeting neutral ships, deeply angered the American public.
Public outrage against Germany’s actions, coupled with a growing sense of moral obligation to aid the Allies, chipped away at American isolationist sentiment.
President Woodrow Wilson, previously hesitant to involve the U.S. in the European conflict, used the Zimmermann Telegram as a rallying cry to convince Congress to declare war on Germany in April 1917.
While the telegram didn’t directly cause the other options, it did have a cascading effect:
B. Tensions between the U.S. and Mexico: The telegram undoubtedly strained العلاقات الثنائية, but the war declaration came due to Germany’s actions, not Mexico’s potential involvement.
C. The end of the war in Europe: The telegram had no direct bearing on the war’s end, which came 18 months later in November 1918.
D. The beginning of unrestricted submarine warfare: The telegram mentioned this planned resumption, but it was a separate decision made earlier by Germany.
Therefore, the Zimmermann Telegram’s most direct and significant consequence was pushing the U.S. out of isolationism and into World War I.