The correct answer is: D. near full load.
An induction motor has relatively high power factor at near full load. This is because the power factor is a measure of how efficiently the motor converts electrical energy into mechanical energy. At near full load, the motor is operating at its most efficient point and therefore has the highest power factor.
At no load, the motor is not producing any mechanical power and therefore has a power factor of 0. At 20 percent load, the motor is still not producing much mechanical power and therefore has a power factor that is still relatively low. At rated r.p.m., the motor is operating at its maximum speed, but it may not be operating at its maximum load. Therefore, the power factor at rated r.p.m. may not be as high as the power factor at near full load.
In conclusion, the correct answer is: D. near full load.