Soldiers returning to the united states who used high-quality while in vietnam discontinued use when they were no longer confronted by the anxiety and depression of the war experience.
a. cocaineb. marijuanac. alcohold. heroin

d. heroin

Explanation:

In the early 1970's, there was argued to be a distinctive heroin problem among  American troops in Vietnam.  

It was discovered that there were heroin addicts from over 15 percent of  American troops deployed there.  

The finding resulted in a burst of activity, including the establishment of  President Nixon's Special Action Office for Drug Abuse Prevention,  promoting prevention and recovery, and tracking addicted military members back  home.

answer; ha,ha,ha, corn on the cop;