The correct answer is: D. Universal motor
A universal motor is a type of electric motor that can be powered by both direct current (DC) and alternating current (AC). It is a series-wound motor, which means that the field winding and the armature winding are connected in series. This type of motor has a high starting torque, which makes it ideal for use in applications where a large amount of torque is required at startup, such as vacuum cleaners and power tools.
A DC shunt motor is a type of electric motor that is powered by direct current. It has a shunt field winding that is connected in parallel with the armature winding. This type of motor has a low starting torque, but it has a high speed regulation.
A Schrage motor is a type of electric motor that is powered by alternating current. It has a squirrel-cage rotor and a wound stator. This type of motor has a high starting torque and a high speed regulation.
A repulsion start and induction run motor is a type of electric motor that is powered by alternating current. It has a squirrel-cage rotor and a stator with two windings: a main winding and a starting winding. The starting winding is connected in parallel with the rotor winding, and it is used to provide the starting torque. Once the motor is up to speed, the starting winding is disconnected, and the motor runs as an induction motor.
In conclusion, the universal motor has the highest starting torque of the four motors listed.