The correct answer is: A. slip rings
A repulsion motor is a type of electric motor that uses slip rings to connect the rotor windings to the external circuit. The slip rings allow the rotor to rotate without breaking the electrical connection to the external circuit. This is necessary because the rotor is constantly changing speed, and the external circuit needs to be able to keep up with the changes in speed.
A slip ring is a type of electrical connector that allows for the transfer of power and/or signals between a rotating and stationary part of a machine. Slip rings are typically used in applications where the rotating part is not directly connected to the stationary part, such as in electric motors and generators.
A commutator is a device that is used to reverse the current in the rotor windings of a DC motor. The commutator is made up of a series of copper segments that are insulated from each other. The segments are connected to the rotor windings, and the brushes are used to make contact with the segments. As the rotor rotates, the brushes make contact with different segments, which reverses the current in the rotor windings. This causes the rotor to turn in the opposite direction.
In conclusion, a repulsion motor is equipped with slip rings, not commutators.