A double squirrel-cage induction motor has, O A. Two parallel windings in the rotor O B. Two rotors moving in opposite directions O C. Two series windings in the stator O D. Two parallel windings in the stator The speed of a squirrel cage induction motor can be controlled by all of the following except, O A. Reducing supply voltage O B. Changing supply frequency C. Changing the number of poles O D. Changing winding resistance