The correct answer is A. interchanging the supply leads.
An hysteresis motor is a type of single-phase induction motor that uses hysteresis to create a rotating magnetic field. The direction of rotation of the motor is determined by the direction of the current in the stator windings. By interchanging the supply leads, the direction of the current in the stator windings is reversed, and the direction of rotation of the motor is also reversed.
Option B is incorrect because the position of the shaded pole with respect to the main pole does not affect the direction of rotation of the motor. The shaded pole is used to create a rotating magnetic field, but the direction of rotation of the field is determined by the direction of the current in the stator windings.
Option C is incorrect because the retentivity of the rotor material does not affect the direction of rotation of the motor. The retentivity of the rotor material is a measure of how well the rotor material retains its magnetism, but this does not affect the direction of rotation of the motor.
Option D is incorrect because all of the above factors affect the direction of rotation of the motor. The direction of rotation of the motor is determined by the direction of the current in the stator windings, the position of the shaded pole with respect to the main pole, and the retentivity of the rotor material.