The us loss in vietnam was a war "lost at home," just as the was a war "lost at home."
a. greek civil war
b. chinese civil war
c. soviet loss in afghanistan
d. north korean loss in south korea

I believe the answer is: B. chinese civil war.
Both Chinese civil war and the Vietnam war carried out a similar philosophy that become the reason of the war.
They both happened due to the clash of ideology between communism and Democracy.