What is detoxification? A.
gradual and complete withdrawal from a drug under medical supervision
B.
gradual withdrawal from a drug by replacing the abused drug with one that produces the same effects
C.
a drug addict not using the drug for a period of 15 days or more.

A.  gradual and complete withdrawal from a drug under medical supervision

Explanation:

The question above is related to "drug addiction." In order to manage a drug addict and his withdrawal symptoms, it is important to "detoxify" him. Gradual withdrawal is important in order to prevent the person from experiencing dangerous drug-withdrawal symptoms; so this is done under medical supervision until such time that the person's body will be free from drugs. This is also the same with alcohol addiction.

This process may last to many months depending on the type of drug that the user used.

answer; all of the above;