Kant's "Categorical Imperative" Said Which of the Following

Kant's "categorical imperative" said which of the following?

A) Justice is possible when decisions are made without considering the social status of the people involved.
B) Ethical behavior comes from striking a balance between excess and defect.
C) That which is virtuous provides the greatest happiness for the greatest number.
D) You should act as though what you do will become a universal law.