Final answer:
Palladium (Pd) is the metal among the provided elements and it is classified as a transition metal.
Step-by-step explanation:
Among the options provided (Br, B, Ar, Pd), Palladium (Pd) is a metal. Specifically, palladium is a transition metal, which is a class of metals characterized by their ability to form compounds with varying oxidation states. Other examples of transition metals include iron (Fe) and copper (Cu), which are well-known for their conductive properties and wide use in industry and electronics. Palladium itself is used in catalytic converters, electronics, and as an investment medium in the form of bullion coins and bars.