When oxygen reacts with non-metals, it forms oxides. These oxides can have different properties based on their reaction with water (to form acids or bases) or their behavior as a Lewis acid or base.

Option 1: Basic Oxides - These are oxides that react with water to form bases. They increase the pH when dissolved in water. Since the question mentions that oxygen reacts with non-metals, basic oxides are not formed in this case.

Option 2: Acidic Oxides - These are oxides that react with water to form acids. They decrease the pH when dissolved in water. This option is correct because oxygen does indeed form acidic oxides when it reacts with non-metals.

Option 3: Amphoteric Oxides - These are oxides that can act as both acids and bases, depending on the reaction conditions. Oxygen does not typically form amphoteric oxides when it reacts with non-metals.

Option 4: Neutral Oxides - These are oxides that neither react with water to form acids nor bases. Oxygen does not form neutral oxides when it reacts with non-metals.

Therefore, the correct answer is option 2, acidic oxides.