Why Are Amphetamines the Most Serious Drug Problem in Japan

Why are amphetamines the most serious drug problem in Japan?

A) Amphetamines are readily available as over-the-counter diet aids.
B) There is a limited amount of land for cultivation of plant-based drugs; since amphetamines are synthetic drugs,they are more easily available.
C) Government agencies have managed to intercept most shipments of drugs that have a detectable odor.
D) These drugs have a long history of use by people who want to boost their energy so that they can work an increased number of hours.