Welding Which statement concerning a welding process is true? a. The inert-arc welding process uses an inert gas to protect the weld zone from the atmosphere. b. In the metallic-arc welding process, filler material, if needed, is provided by a separate metal rod of the proper material held in the arc. c. In the oxyacetylene welding process, the filler rod used for steel is covered with a thin coating of flux.