In a shaded-pole motor, what characteristic defines the salient pole?

The characteristic that defines a salient pole in a shaded-pole motor is that it projects above the stator core. Salient poles are prominent or extended structures that help create a magnetic field necessary for the motor's operation. The design of salient poles facilitates the generation of a strong magnetic field, which is essential for the motor to function effectively.

This projection above the stator allows for the necessary interaction with the rotor, creating the torque needed to maintain motion. In contrast, other options do not specifically relate to the fundamental design characteristic of a salient pole. For example, while a shaded-pole motor does produce a magnetic field, it is not accurate to call it a main power source, nor is it primarily designed to reduce noise or enhance efficiency in the same way that other motor designs might do. The salient pole's unique structure is its defining feature, which is why projecting above the stator core is the correct answer.