The correct answer is: A. Shunt motor
A shunt motor is a type of DC motor that has a shunt field winding connected in parallel with the armature winding. The shunt field winding provides a constant magnetic field, which produces a constant torque on the armature. This means that the speed of a shunt motor is relatively constant, regardless of the load.
A series motor is a type of DC motor that has a series field winding connected in series with the armature winding. The series field winding provides a variable magnetic field, which produces a variable torque on the armature. This means that the speed of a series motor is inversely proportional to the load.
A cumulative compound motor is a type of DC motor that has both a shunt field winding and a series field winding. The shunt field winding provides a constant magnetic field, while the series field winding provides a variable magnetic field. This means that the speed of a cumulative compound motor is somewhere between the speed of a shunt motor and the speed of a series motor.
A differential compound motor is a type of DC motor that has both a shunt field winding and a series field winding. The shunt field winding provides a constant magnetic field, while the series field winding provides a variable magnetic field in the opposite direction. This means that the speed of a differential compound motor is less than the speed of a shunt motor.
In conclusion, the no-load speed of a shunt motor is highest because the shunt field winding provides a constant magnetic field, which produces a constant torque on the armature.