The correct answer would be the third option. In order for the equilibrium of the reaction to shift to the left, we must decrease the concentration of a reactant or increase the concentration of the product. This is based on Le Chatelier's principle which describes the effect on equilibrium of changes in concentration or pressure of a product or a reactant. Adding more product in a system, would disturbed the equilibrium thus it would cause to reestablish it by shifting the reaction to the left producing the reactants. This would also be the same when you decrease the amount of reactant in the system.