The correct answer is D. 90°.
A capacitor start motor is a type of single-phase induction motor that uses a capacitor to create a phase difference between the starting and running windings. This phase difference causes the motor to start rotating. The capacitor is usually connected in parallel with the starting winding, and it is removed from the circuit once the motor has reached a certain speed.
The phase displacement between the starting and running windings is typically around 90°. This means that the current in the starting winding is 90° out of phase with the current in the running winding. This phase difference creates a rotating magnetic field that causes the motor to start rotating.
The other options are incorrect because they do not represent the typical phase displacement between the starting and running windings in a capacitor start motor.