The correct answer is A. running winding.
A single-phase induction motor has two windings: a main winding and a starting winding. The main winding is connected to the power supply and produces a rotating magnetic field. The starting winding is connected to the power supply for a short time to help the motor start. Once the motor is up to speed, the starting winding is disconnected from the power supply and the motor continues to run on the main winding.
The rotor winding is the winding that is located on the rotor of the motor. The rotor winding is not connected to the power supply. Instead, it is induced to rotate by the magnetic field produced by the main winding.
The field winding is the winding that is located on the stator of the motor. The field winding is connected to the power supply and produces the magnetic field that induces the rotor winding to rotate.
The compensating winding is a winding that is sometimes used in single-phase induction motors to reduce noise and vibration. The compensating winding is connected in parallel with the main winding and helps to stabilize the magnetic field.
In conclusion, after the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on the running winding.