The correct answer is: C. Fall out of synchronism and come to stand still.
A reluctance motor is a type of synchronous motor that uses the principle of reluctance to produce torque. The rotor of a reluctance motor is made up of a number of poles that are arranged in a stator field. When the stator field is energized, the rotor poles align with the stator field, and the motor turns.
If the load on the motor is increased, the rotor will tend to fall out of synchronism with the stator field. This is because the rotor poles will no longer be aligned with the stator field, and the motor will not be able to produce torque. The motor will continue to turn, but it will not be able to maintain synchronous speed.
If the load on the motor is increased further, the rotor will fall out of synchronism completely and come to a standstill. This is because the rotor poles will no longer be aligned with the stator field, and the motor will not be able to produce any torque.
Options A, B, and D are incorrect because they do not accurately describe what will happen to a reluctance motor when the load is increased so that it cannot maintain synchronous speed.