The correct answer is A) stranded wire increases their flexibility over solid wire and reduces skin effect losses. The reason is that stranded wire, which is composed of multiple smaller individual wires twisted together, is more flexible than a solid wire of the same overall diameter. This increased flexibility is advantageous for applications where the cable needs to be bent or routed through tight spaces. Additionally, the stranded construction helps to reduce skin effect losses, which is the tendency for alternating current to flow primarily on the outer surface of a conductor. By using stranded wire, the current is distributed more evenly across the cross-section of the conductor, improving the overall efficiency. The other options are incorrect because B) is about current carrying capability, C) is about weight, and D) is about conductivity at junctions, which are not the primary reasons for using stranded wire.