Answer:
None of the options here are good.
Explanation:
American public opinion was divided and there were many views before the war.
The US joined the Allied effort, so nobody thought it could win alone.
Economic benefit was never a major thinking current in public opinion in the USA.
People didn´t expect their country to suffer so many casualties, but that a country will suffer causalties if it enter a war is obvious.
When the US entered WWI, the conflict had been going on for 3 years already, so people could not expect the war to be short-lived.
