What is the configuration of a shaft used to transmit power or motion?

A shaft is a rotating element, usually of circular cross-sectional shape, used to transmit power or motion.
The configuration of a shaft is generally that of a stepped cylinder.
The use of shoulders or protrusions is an excellent means of axially locating the elements of the shaft and for executing any necessary thrust load.
a) Only statement A is correct.
b) Statements A and B are correct.
c) Statements A and C are correct.
d) All statements are correct.