Final answer:
The country where U.S. troops are supposed to be engaged in helping the government to destroy opium poppies is D. Afghanistan.
Step-by-step explanation:
Opium poppies are the source of opium, which can be further refined into heroin. Afghanistan is the world's largest producer of opium, and the drug trade has been a significant issue in the country, contributing to its income and causing various problems.
The U.S. government has been supporting the Afghan government in the fight against drug cartels and the trafficking of illegal drugs. Therefore U.S. troops are supposed to be engaged in helping the government of Afghanistan to destroy opium poppies. The correct answer is D. Afghanistan.