Immanuel Kant -Kant Proves the Freedom of the Will and the Capacity

Immanuel Kant
-Kant proves the freedom of the will and the capacity for reason in people by arguing that

A) the idea of morality necessitates a free will.
B) freedom of the will is an a priori concept in our minds,much like the concept of causality.
C) for morality to be possible,we must have reason and be free.
D) None of the above.Kant admits that no proof can be made that does not beg the question.