Final answer:
These events contributed to the outbreak of World War II.
Step-by-step explanation:
The Zimmerman Note, unrestricted submarine warfare, and the sinking of the Lusitania are all causes of WWII. The Zimmerman Note was a secret diplomatic communication sent by Germany to Mexico, proposing a military alliance against the United States. Unrestricted submarine warfare was a strategy used by Germany to sink ships, including the passenger liner Lusitania. These events contributed to the escalation of tensions and ultimately led to the outbreak of World War II.
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