Around 20% of all yearly deaths in the united states can be attributed to chronic use.
a. tobacco
b. heroin
c. cocaine
d. marijuana

Around 20% of all yearly deaths in the United States can be attributed to chronic tobacco use.

Explanation:

Despite heroin and cocaine are stronger drugs, that more easily can lead to death, the chronic tobacco use is what causes around 20% of all yearly deaths, because it's most commonly used than heroin and cocaine.

On the other hand, we also have marijuana, which it doesn't have the death percentage shows, because marijuana is a drug that doesn't lead to death. So, the right answer is tobacco for sure.

Around 20% of all yearly deaths in the United States can be attributed to chronic tobacco use.