Immanuel Kant -Since No Person or Persons Have Ever Done Anything Out

Immanuel Kant
-Since no person or persons have ever done anything out of duty alone,it follows that

A) moral perfection is unattainable and therefore,the standards of morality ought to be tempered by practical reason.
B) duty is determined independently of individual circumstances,regardless of whether or not it can be lived up to.
C) there is no such thing as absolute morality,since there is not example of it in the world.
D) morality must be determined by duty and the expected result.