Copper Can Be Separated from Iron in the Ore Chalcopyrite $\rarr$

Multiple Choice

Copper can be separated from iron in the ore chalcopyrite (CuFeS₂) by heating the ore in the presence of oxygen to form copper(I) sulfide, iron(II) oxide, and one other product. Complete the following partially balanced equation by deciding both the identity of the missing compound and the number of moles required to balance the equation. (Note, no other coefficients are allowed to be changed.)
2CuFeS₂(s) + 4O₂(g) $\rarr$ Cu₂S(s) + 2FeO(s) + _____

A) 2SO₃(g)
B) 3SO₃(g)
C) 2SO₂(g)
D) 3SO₂(g)
E) None of the above