The correct option is A -2
Sodium sulphate(Na2SO4), a salt, is an ionic compound. Being an ionic compound, on dissociation, it produces a negatively charged anion and a positively charged cation. In the case of Na2SO4, sodium(Na+) is the cation and sulphate(SO24−) is the anion. Hence, the charge of anion in this case is -2.