What is the reason that some electric cables are formed of stranded wire?

Correct Answer: Option D — stranded wire increases their flexibility over solid wire and reduces skin effect losses

Stranded conductors provide the mechanical flexibility necessary to withstand shipboard vibration and thermal expansion without fatigue failure. Furthermore, at higher frequencies, current tends to flow near the conductor surface; stranding increases the effective surface area, which helps mitigate skin effect losses compared to a single solid conductor.