p-Block

Among Al2O3, SiO2, P2O3 and SO2 the correct order of acid strength is

Among Al₂O₃, SiO₂, P₂O₃ and SO₂ the correct order of acid strength is

1. Al₂O₃ < SiO₂ < P₂O₃ < SO₂
2. Al₂O₃ < SiO₂ < SO₂ < P₂O₃
3. SiO₂ < SO₂ < Al₂O₃ < P₂O₃
4. SO₂ < P₂O₃ < SiO₂ < Al₂O₃