The answer is C. A drug is any substance that alters the normal functioning of the body.
A drug is any substance other than the nutrients essential for body changes the normal functioning of the body. It may be physiological or biological which is temporary. A drug is used in the diagnosis, treatment or prevention of a disease to relief the discomfort. A drug producing a state to relief the discomfort. A drug producing a state of casual when used in continuation or in excessively causes addiction known as drug abuse.
One way in which classification is used at school is the separation of different subjects and subject materials. For instance one day you may go to a math class, while another day you may go to a french class.
