The immediate causes of the 1812 war were a series of economic sanctions taken by the British and French against the US.
The Opium Wars were a series of wars between Chine and Great Britain. It started when Chine started to refuse the shipments of Opium. The war was a fail for China, this means that answer A, C, and D are wrong. The only answer left is B. Please contact me if you want more information on the opium war.
Hope this Helps! :)
Answer:
1. United States ships were getting sunk by German U-Boat warfare
2. Inability to remain neutral
3. Zimmerman Telegram of 1917
4. U.S. economic and political ties to Great Britain