C. Some people believed that the prohibition of alcohol was unconstitutional.
Explanation:
The 18th Amendment was put into use in 1919, and the purpose of this was to make alcohol illegal. This was brought to attention by the activists who believed that banning alcohol would make a better society, but when this went into play people were not happy. People believed that it was unconstitutional and not right to make alcohol illegal, as it was very popular during this time. The 18th Amendment later got repealed by the 21st Amendment in 1933, making it the only Amendment to ever be taken back by the Constitution.
Congress was completely ineffective in preventing the Civil War because the Southern states still seceded. This option is best drawn because of the fact that that in the case of the 2nd option, they did not delay the war in any way. It was only a matter of time until the war happened, and nothing could have stopped it from happening. Once the Southern states made the decision to secede, the war was inevitable.