Change in volume of the system does not alter the number of moles in which of the following equilibrium

Let us consider the change in moles of given reactions as follows- In option A, number of moles of product – reactant= 2- 2= 0 In option B, number of moles of product – reactant= 2- 1=1 In option C, number of moles of product – reactant= 2- 4=-2 In option D, number of moles of product – reactant= 2- 1=1 Clearly in option A, the number of moles on both reactant and product side are same. Therefore, any change in volume doesn’t affect it.