Immanuel Kant's Work Is Considered Fundamental in What Sense

Immanuel Kant's work is considered fundamental in what sense?

A) It establishes the association between virtue, enlightenment, and reason as the basis of good governance.
B) It establishes the link between the state of nature, the social contract, and best practice in government.
C) It considers international frameworks to develop one of the earliest formulations of liberal foreign policy.
D) It invokes utilitarian principles as the foundation for protecting liberty and the specification of law by measuring and identifying best approaches in any situation.