The correct option is
D Stimulants
Barbiturates are CNS (Central nervous system) depressants. They are sedative-hypnotic drugs as they reduce anxiety and excitement and induce sleep. They lower the functional and physiological activity that leads to drowsiness or sleep. Barbiturates are derivatives of barbituric acid. If they are taken in excess amount, they cause permanent damage to brain.
So, the correct answer is 'Stimulants'.