The correct answer is: D. None of the above
A series generator, shunt generator, and compound generator all require residual magnetism in the poles to build up a voltage. Without residual magnetism, there would be no current in the field winding, and no voltage would be induced in the armature winding.
Residual magnetism is the small amount of magnetism that remains in the poles of a generator after it has been turned off. This magnetism is caused by the alignment of the magnetic domains in the iron of the poles. When the generator is turned on, the current in the field winding causes the magnetic domains to align in the same direction, creating a stronger magnetic field. This stronger magnetic field induces a voltage in the armature winding, which creates a current that flows through the field winding. This current further strengthens the magnetic field, and the process continues until the generator reaches its rated voltage.
If there was no residual magnetism, the generator would not be able to build up a voltage. This is because the current in the field winding would be zero, and there would be no magnetic field to induce a voltage in the armature winding.
In conclusion, none of the above generators will be in a position to build up without any residual magnetism in the poles.