Correct Answer : Option (D) : All of the above
Explanation : Thermit welding is a welding process that employs molten metal to permanently join the conductors.
The process employs an exothermic reaction of a thermite composition to heat the metal, and requires no external source of heat or current.
Thermit welding is often used in replacing broken gear teeth, repairing broken shears and joining rails, truck frames and locomotive frames etc.
