Which of the following events directly influenced the United States to enter the First World War?

While the armistice between Russia and Germany did impact the Eastern Front of the war, it did not directly influence the United States' decision to enter the conflict. The U.S. was primarily concerned with its own security and the direct threats posed by Germany, making this event more of a secondary concern.

The invasion of the Philippines by Japanese forces was not a factor in the United States' entry into World War I. This event is more relevant to U.S.-Japan relations and the Pacific theater, rather than the European conflict that primarily influenced American involvement in the Great War.

Although the bombing of London by German planes was significant in raising awareness of German aggression, it was the specific communication of the Zimmermann telegram that directly implicated the U.S. in the war. The attacks on London did not provide the same immediate and personal threat to American citizens or interests as the revelation of the telegram did.