Aluminium oxide, option 1, is classified as an amphoteric oxide because it reacts with both acids and bases. When aluminium oxide comes into contact with an acid, it works as a base, neutralizing the acid. Conversely, when it encounters a base, it behaves as an acid, neutralizing the base.

Option 2, Calcium oxide, reacts with acids only and not with bases, so it`s a basic oxide. Sodium oxide and Potassium oxide, options 3 and 4, are also basic oxides, meaning they react with acids but not with bases. Thus, only aluminium oxide meets the criteria given in the question, making it the correct answer.