The correct answer is: C. Aluminium.
An amphoteric oxide is an oxide that can react both as an acid and a base. This means that it can react with both acids and bases to form salts.
Aluminium oxide (Al2O3) is an amphoteric oxide. It can react with acids to form aluminium salts, such as aluminium chloride (AlCl3). It can also react with bases to form aluminium hydroxide (Al(OH)3).
Sodium (Na) is a metal that forms a basic oxide, sodium oxide (Na2O). Silver (Ag) is a metal that forms a basic oxide, silver oxide (Ag2O). Calcium (Ca) is a metal that forms a basic oxide, calcium oxide (CaO).
Therefore, the only metal that provides an amphoteric oxide is aluminium.