The correct answer is: D. none of the above.
A universal motor is a type of electric motor that can operate on either direct current (DC) or 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 and can be used in a variety of applications, such as vacuum cleaners, power tools, and food mixers.
The speed/load characteristics of a universal motor are different from those of a DC motor. A DC motor has a constant speed when the load is changed. A universal motor, on the other hand, has a speed that decreases as the load increases. This is because the current through the field winding increases as the load increases, which causes the magnetic field to weaken. This weakening of the magnetic field causes the motor to slow down.
The speed/load characteristics of a universal motor are also different from those of a DC shunt motor. A DC shunt motor has a constant speed when the load is changed. This is because the current through the field winding is independent of the load current. The field winding is connected in parallel with the armature winding, so the current through the field winding is the same regardless of the load current.
The speed/load characteristics of a universal motor are also different from those of a DC series motor. A DC series motor has a speed that increases as the load increases. This is because the current through the field winding and the armature winding are in series. As the load increases, the current through both windings increases. This increase in current causes the magnetic field to strengthen, which causes the motor to speed up.