Define Act Utilitarianism

Define act utilitarianism.

A) Act utilitarianism is the view that an action is right if and only if it maximizes the total happiness in the world, counting everyone's happiness equally.
B) Act utilitarianism is the view that an action is right if and only if it maximizes both the quantity and the quality of pleasure in the world, counting everyone's happiness equally.
C) Act utilitarianism is the view that an action is right if and only if, relative to other available actions, it produces happiness for the greatest number of people.
D) Act utilitarianism is the view that an action is right if and only if it benefits people in proportion to their usefulness to society.