The correct answer is A. Commutator.
A commutator is a device that is used to convert the alternating current (AC) produced by a rotating coil of wire into direct current (DC). It does this by reversing the polarity of the current at the correct time so that the current always flows in the same direction.
The commutator consists of a series of metal rings that are insulated from each other. The armature coil is connected to the commutator rings through brushes. As the armature coil rotates, the brushes make contact with different commutator rings, which reverses the polarity of the current.
The commutator is a critical component of a DC generator. Without it, the generator would produce AC current, which is not suitable for many applications.
The other options are incorrect.
- Solid connection: This would not allow the current to flow in the correct direction.
- Slip rings: These are used to connect a rotating shaft to a stationary circuit. They would not be able to reverse the polarity of the current.
- None of the above: This is not an option.