Tunnel vision is caused by

Which of the following pairs is correctly matched?

Excessive dosage of cocaine causes

Which of the following substances inhibits brain activity and produces feelings of relaxation,drowsiness,and calmness?

The chemical structure of a drug is given below:
$(a)$ Which group of drugs does this represent?
$(b)$ What are the modes of consumption of these drugs?
$(c)$ Name the system of the body which is affected by the consumption of these drugs.

In a young addict,symptoms such as inhibition of brain activity,calming of the brain,and feelings of relaxation are observed. Which drug is he likely consuming?