After Balancing the Following Reaction Under Basic Conditions , How

After balancing the following reaction under basic conditions , how many mole equivalents of hydroxide are required and on which side of the reaction do they appear?
SO₃^{2 -} (aq) + Cl₂ (g) →SO₄^{2 -} (aq) + Cl^{1 -} (aq) [Basic conditions]

A) 2 moles of OH ^- on the reactant side
B) 2 moles of OH ^- on the product side
C) 5 moles of OH ^- on the product side
D) 5 moles of OH ^- on the reactant side
E) 10 moles of OH ^- on the reactant side