What Is Meant by the Term Vietnam Syndrome

What is meant by the term Vietnam syndrome?

A) Many veterans of the Vietnam War suffered from posttraumatic stress disorder.
B) American leaders exaggerated the importance of Vietnam,so afterward the American public did not believe their warnings of other dangers.
C) The Vietnam War was the first of a long line of wars in which U.S.leaders lied to the American public about the reasons for military intervention.
D) The Vietnam War was the closest the world has ever come to nuclear holocaust,which prompted U.S.leaders to take nuclear disarmament more seriously.