Sulphur dioxide is one of the components of polluted air. SO$$_2$$ is also a major contributor to acid rain. The correct and complete reaction to represent acid rain caused by SO$$_2$$ is:

We need to identify the correct and complete reaction representing acid rain caused by SO₂. SO₂ in the atmosphere undergoes oxidation and reacts with water to form sulphuric acid (H₂SO₄), which falls as acid rain.

Option A: $$2\text{SO}_2 + \text{O}_2 \rightarrow 2\text{SO}_3$$ — This only shows the oxidation of SO₂ to SO₃, not the complete acid rain reaction. Option B: $$\text{SO}_2 + \text{O}_3 \rightarrow \text{SO}_3 + \text{O}_2$$ — This uses ozone as oxidizer and still does not produce acid rain (no H₂SO₄). Option C: $$\text{SO}_2 + \text{H}_2\text{O}_2 \rightarrow \text{H}_2\text{SO}_4$$ — This produces H₂SO₄ but uses H₂O₂, which is not the primary pathway. Option D: $$2\text{SO}_2 + \text{O}_2 + 2\text{H}_2\text{O} \rightarrow 2\text{H}_2\text{SO}_4$$ — This is the complete reaction showing SO₂ being oxidized and combined with water to form sulphuric acid.

Option D represents the correct and complete reaction for acid rain caused by SO₂, so the answer is Option D: $$2\text{SO}_2 + \text{O}_2 + 2\text{H}_2\text{O} \rightarrow 2\text{H}_2\text{SO}_4$$.