Correct option is C
Bundled conductors are used in high-voltage power lines to reduce various undesirable effects and improve performance. Let's evaluate the characteristics listed:
Reduced radio interference: Bundled conductors help in reducing radio interference by decreasing the corona discharge.
Reduced voltage gradient: Bundled conductors reduce the voltage gradient at the surface of the conductors, which helps in reducing corona losses.
Reduced cost of construction: This is not a valid advantage. In fact, the cost of construction is usually higher for bundled conductors compared to single conductors due to the complexity and additional materials required.
Reduced surge impedance: Bundled conductors do reduce surge impedance, which improves the transmission line performance.
Therefore, the correct answer is Reduced cost of construction.
