The correct answer is C. Both (A) and (B).
The thickness of insulation provided on the conductor depends on the magnitude of voltage on the conductor and the magnitude of current flowing through it. The higher the voltage, the thicker the insulation needs to be to prevent the conductor from arcing. The higher the current, the thicker the insulation needs to be to prevent the conductor from overheating.
Option A is correct because the higher the voltage, the greater the potential for arcing. Arcing is a phenomenon that occurs when a high-voltage current jumps across a small gap between two conductors. This can cause damage to the insulation and even start a fire. To prevent arcing, the insulation needs to be thick enough to withstand the voltage.
Option B is correct because the higher the current, the greater the heat generated. This heat can cause the insulation to melt or catch fire. To prevent this, the insulation needs to be thick enough to withstand the heat generated by the current.
Option D is incorrect because both the voltage and the current affect the thickness of insulation required.