The correct answer is A. Stoic.
A stoic is a person who is indifferent to pains and pleasure of life. They believe that the only thing that is truly important is to live in accordance with nature, and that one should not be attached to either pleasure or pain.
A sadist is a person who derives pleasure from the pain of others.
A psychiatrist is a medical doctor who specializes in the diagnosis and treatment of mental disorders.
An aristocrat is a person who belongs to the highest social class.
Stoicism is a school of philosophy that teaches that happiness can be found by accepting the moment as it presents itself, by not allowing oneself to be controlled by the desire for pleasure or fear of pain, and by using one’s mind to understand the world and to do one’s part in nature’s plan.