What Was the Main Impression Brought Back by the Doughboys

What was the main impression brought back by the doughboys?

A) War was a disillusioning and useless experience, and America's crusade to save the world a fraud.
B) War was a racially enlightening experience that taught tolerance of diversity.
C) Europe was the more fascinating place, with a superior culture and heritage.
D) The U.S. was the more vital and modern civilization.