Final answer:
The Zimmerman Note, unrestricted submarine warfare, and the sinking of the Lusitania were causes of WWI.
Step-by-step explanation:
The causes of WWI include the Zimmerman Note, unrestricted submarine warfare, and the Sinking of the Lusitania. The Zimmerman Note was a secret message sent by Germany to Mexico proposing an alliance, which was intercepted by the British. Unrestricted submarine warfare was a policy adopted by Germany to sink any ship, including non-military vessels, in order to cut off supplies to their enemies. The Sinking of the Lusitania was an event where a British passenger ship was torpedoed by a German U-boat, resulting in the loss of many lives. These factors contributed to the outbreak of World War I.
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