Correct option is A
In the brazing process, flux is used to prevent the base metal from oxidizing and melting while heat is applied to melt the filler metal. Flux also promotes wetting of the base metal by the molten filler, ensuring a strong joint. Unlike welding, the base metal is not melted in brazing; flux helps protect it during the heating process. Assembly refers to the arrangement of parts, and a furnace is simply the heat source.
