Weber Credits Martin Luther with Developing the Idea of a "Calling

Weber credits Martin Luther with developing the idea of a "calling," which claims that

A) we are all destined to enter heaven.
B) at a critical point in our life, we will "know God" as true.
C) God expects us to willingly engage in work as a sign or manifestation of our morality.
D) a select few people are designated to lead the rest of the people in righteousness.