In a cable the voltage stress is maximum at

Answer: Option C

In a cable, the voltage stress refers to the electrical stress experienced by the materials within the cable when it is subjected to an electric field. The voltage stress is maximum at the surface of the conductor. This is due to the phenomenon known as the skin effect.

The skin effect causes the distribution of current within a conductor to be concentrated near the surface when the frequency of the electrical signal is high. As a result, the majority of the current flows through a thin layer near the surface of the conductor, leading to a higher voltage stress at the surface compared to the core.

Therefore, Option C correctly identifies that the voltage stress is maximum at the surface of the conductor in a cable.