The correct option is
D Deriving pleasure from inflicting pain on others
'Sadistic' means a person who gets pleasure by hurting another person.
Option A - 'Smart' means having a clean, tidy and stylish appearance. Thus option A is incorrect.
Option B - 'Using others for personal gain' means a person who is similar to a leech. Such person can be called 'selfish'. Thus option B is incorrect.
Option D - 'Depressed' means someone who is unhappy and without hope. Thus option D is incorrect.
Option C - 'Deriving pleasure from inflicting pain on others' means someone who gets pleasure or happiness by harming or hurting others. Thus option C is the correct answer.
'Sadistic - Deriving pleasure from inflicting pain on others'