Final answer:
President Wilson asked Congress to declare war on Germany in 1917 due to strategic concerns after German unrestricted submarine warfare, the interception of the Zimmermann Telegram signaling German encouragement of a Mexican attack on the U.S., and the Russian Revolution which eased moral hesitations. The correct option is b. he was concerned about the german aggression outlined in the Zimmermann note.
Step-by-step explanation:
President Wilson was initially determined to maintain the United States neutrality during World War I. However, in 1917, there were several events that shifted his stance. The unrestricted submarine warfare by Germany, which included the sinking of American ships, and the Zimmermann Telegram, which revealed German intentions to ally with Mexico against the U.S., both severely challenged American neutrality and national security.
Moreover, the Russian Revolution effectively removed one of the moral barriers for the U.S. to support the Allies, as the autocratic tsar was replaced with a provisional government.
Consequently, Wilson asked Congress to declare war on Germany, believing that a German victory would upset the balance of power in Europe to the detriment of the United States and its interests. The correct option is b. he was concerned about the german aggression outlined in the Zimmermann note.