Correct option is D
In residential distribution systems, electric power must supply:
Single-phase loads (lighting, fans, domestic appliances)
Occasional three-phase loads (lifts, water pumps, large HVAC systems in apartment complexes)
To meet both requirements efficiently, utilities use a three-phase four-wire distribution system:
The system consists of three phase conductors and one neutral conductor.
Single-phase consumers are connected between any one phase and the neutral (e.g., 230 V in India).
Three-phase loads, where required, are connected across all three phases.
