Predict the classification of silicon and elaborate on the reasoning. A) Silicon is a noble gas and has a full valence electron shell, is chemically non-reactive, colorless, odorless, and is a gas at room temperature. B) Silicon is a metal and is shiny, malleable, ductile, conducts heat and electricity, forms basic oxides, and forms cations in aqueous solution. C) Silicon is a nonmetal and is dull, brittle, poor conductor of heat and electricity, forms acidic oxides, and forms anions in aqueous solution. D) Silicon is a metalloid and has properties of both metals and nonmetals - it appears lustrous, but is brittle and a poor conductor of heat and electricity.