The use of illegal drugs peaks around age _____ and declines more sharply than the use of cigarettes and alcohol.

A) 15
B) 18
C) 20
D) 24

The use of illegal drugs typically peaks around age 20, as individuals in this age group are often in environments (such as college) that facilitate experimentation. After this peak, the use of illegal drugs tends to decline more sharply compared to the use of legal substances like cigarettes and alcohol, which may have more socially accepted or habitual use patterns extending into later adulthood.