Drug abuse is best defined as
a.
the consumption of legal drugs
b.
the consumption of illegal drugs
c.
the nonmedical or improper use of a drug that can interfere with a healthy life
d.
using drugs on an occasional basis until mood is altered
the answer is c

Drug abuse is best defined as the nonmedical or improper use of a drug that can interfere with a healthy life.

For example, a person that is addicted to cocaine will use it everyday, and will develope agressive behavior, anxiety, sleep disorder, paranoia etc.

This person could get addicted at the point of comiting a robbery, killing and much more.

Importance: all living organisms need/use water, can be used for ... a process where matter is recycled through specific interactions between biotic and that carbon dioxide is released by breathing out and is returned back to the atmosphere. ... not let heat escape) enters Earth's atmosphere and provides light energy