Less product will form
Equilibrium will remain unchanged
More product will form
More reactant will form
When an inert gas is added to the system in equilibrium at constant volume, the total pressure will increase. But the concentrations of the products and reactants (i.e. ratio of their moles to the volume of the container) will not change. Hence, when an inert gas is added to the system in equilibrium at constant volume there will be no effect on the equilibrium.