Answer:
Options a, b and c.
Explanation:
The reaction of production of SO₂ (sulfur dioxide) is the following:
S + O → SO₂(g) (1)
The SO₂ can be produced by the combustion of materials that contain sulfur, thus the other alternative reactions of formation of SO₂ are the followings:
2H₂S + 3O₂ → 2H₂O + 2SO₂ (2)
4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂ (3)
The reaction (1) is exothermic, it produces temperatures of 1000–1600 °C.
A combination of the reactions (2) and (3) can be found in volcanic eruptions.
Therefore, the correct options are a, b and c. We discard the option d because that reaction produces SO₃ instead of SO₂.
I hope it helps you!