Concept:A semi-metal, also called a metalloid, shows properties between those of metals and non-metals.Explanation:Common semimetals or metalloids include boron, silicon, germanium, arsenic, antimony, tellurium, and polonium.Among the given options, silicon is a metalloid.Carbon is a non-metal.Beryllium is a metal.Argon is a noble gas.Therefore, silicon is the correct example of a semi-metal.Answer:A. silicon