●In thermit welding, molten metal is poured for joining the metals.

●Thermit welding : It is a process in which mixture of iron oxide and granular aluminum is used. This mixture in superheat liquid state is poured around the parts to be joined. The joint is equipped with the refractory mold structure all around. The temperature produced in the thermit reaction is of the order of 3000⁰c.

Hence, the correct option is (D).