Answer:
d. heroin
Step-by-step 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.