Correct option is C
Dielectric heating is a process that uses high-frequency electric fields to heat non-conductive materials, commonly used in applications like wood gluing, preheating of plastics, and electronic sewing. This type of heating is particularly effective for materials that are insulators, as it heats them uniformly by exciting their molecular structure.
Surface hardening, on the other hand, is generally achieved through processes like induction heating or flame hardening, which are different from dielectric heating and are more suitable for metals. Dielectric heating is not typically used for surface hardening, making (c) Surface Hardening the correct answer.
