The correct answer is: A. D.C. series motor.
A D.C. series motor is a type of electric motor that has the field winding and the armature winding connected in series. This means that the same current flows through both windings. This results in a high starting torque, which is why D.C. series motors are often used in applications where a high starting torque is required, such as buses, trains, trolleys, hoists, and cranes.
A D.C. shunt motor is a type of electric motor that has the field winding and the armature winding connected in parallel. This means that the current flowing through the field winding is independent of the current flowing through the armature winding. This results in a lower starting torque than a D.C. series motor, but a higher speed regulation. D.C. shunt motors are often used in applications where a high speed regulation is required, such as machine tools and elevators.
An induction motor is a type of electric motor that has a rotating stator and a stationary rotor. The stator has a three-phase winding that is connected to an AC power source. The rotor has a squirrel cage winding that is not connected to any power source. When the stator winding is energized, it creates a rotating magnetic field. This magnetic field induces a current in the rotor winding, which creates its own magnetic field. The interaction of these two magnetic fields causes the rotor to rotate. Induction motors are often used in applications where a high starting torque is not required, such as fans and pumps.
In conclusion, the correct answer is: A. D.C. series motor.