The correct answer is: A. thick wire placed at the bottom of the slots.
The auxiliary winding is a smaller winding that is used to start the motor. It is made of thicker wire than the main winding and is placed at the bottom of the slots. This allows it to have a higher resistance, which creates a magnetic field that helps to start the motor.
The main winding is a larger winding that is used to run the motor. It is made of thinner wire than the auxiliary winding and is placed at the top of the slots. This allows it to have a lower resistance, which creates a magnetic field that helps to keep the motor running.
The auxiliary winding is only used when the motor is starting. Once the motor is up to speed, the auxiliary winding is turned off and the motor is run by the main winding.
The auxiliary winding is typically made of copper wire. Copper is a good conductor of electricity, which allows it to create a strong magnetic field. The auxiliary winding is also insulated with a material such as enamel or varnish. This insulation protects the wire from damage and prevents it from short-circuiting.
The auxiliary winding is an important part of the split-phase motor. It helps to start the motor and keeps it running smoothly.