The correct answer is A: Lower loss. Parallel conductor transmission line (like ladder line) compared to coaxial cable with a plastic dielectric has lower loss per unit length. Air-insulated parallel line has less dielectric loss than solid-dielectric coax. Parallel conductor line (open-wire, ladder line) typically uses air as the dielectric (or minimal dielectric), which has very low loss. Coaxial cable with solid plastic dielectric has dielectric losses in the insulating material. At HF frequencies, the difference can be significant - parallel line might have 0.1 dB per 100 feet while coax might have 0.5-1 dB per 100 feet. This lower loss is why many operators use open-wire or ladder line for long feed lines, especially at higher power levels where losses become significant. The air dielectric minimizes losses.