Final answer:
The speed of a stator rotating magnetic field of an induction motor is referred to as the synchronous speed. It represents the speed at which the rotating magnetic field of the stator would need to rotate in order to produce the same frequency as the power supply frequency.
Step-by-step explanation:
The correct answer is c) synchronous speed. The speed of a stator rotating magnetic field of an induction motor is referred to as the synchronous speed. In an induction motor, the stator's rotating magnetic field creates a magnetic flux that induces current in the rotor and causes it to rotate. The synchronous speed represents the speed at which the rotating magnetic field of the stator would need to rotate in order to produce the same frequency as the power supply frequency, thus creating a rotating magnetic field that is in sync with the rotor.