Among the given options, Gallium (Ga), Indium (In), and Aluminum (Al) are all metals. Boron (B) is classified as a metalloid, which has properties intermediate between those of metals and nonmetals. However, in many general classifications or in the context of distinguishing from typical metals, Boron is grouped with nonmetals due to its chemical behavior (e.g., forms acidic oxides, covalent compounds). It is the only non-metal or metalloid in the list.