A booster is a

Series wound generator
Shunt wound generator
Synchronous generator
None of the above

The correct answer is: D. None of the above

A booster is a device that increases the voltage of an electrical circuit. It can be used to provide additional power to a load, or to extend the reach of an electrical signal. Boosters can be either AC or DC, and they can be powered by a variety of sources, including batteries, generators, and power lines.

A series wound generator is a type of electric generator that uses a series winding to produce an output voltage. The series winding is connected in series with the load, and the current through the winding creates a magnetic field that induces a voltage in the output terminals.

A shunt wound generator is a type of electric generator that uses a shunt winding to produce an output voltage. The shunt winding is connected in parallel with the load, and the current through the winding creates a magnetic field that induces a voltage in the output terminals.

A synchronous generator is a type of electric generator that uses a rotating magnetic field to induce a voltage in the stator winding. The rotating magnetic field is created by a rotor winding that is excited by a DC current.

In conclusion, a booster is not a series wound generator, a shunt wound generator, or a synchronous generator.