After Balancing the Following Reaction Under Basic Conditions , What

After balancing the following reaction under basic conditions , what is the coefficient for the sulfite species, SO₃^{2 -} ?
SO₃^{2 -} (aq) + Cl₂ (g) →SO₄^{2 -} (aq) + Cl^{1 -} (aq) [Basic conditions]

A) 1
B) 2
C) 3
D) 4
E) 6