In an endothermic reaction, heat is a reactant, meaning it is absorbed for the reaction to proceed towards the products. According to Le Chatelier's principle, if heat is removed from the system, the equilibrium will shift in the direction that produces heat to counteract the change—in this case, it will shift towards the left to favor the formation of the reactants.
Therefore, the correct response is:
The reaction shifts left as the products reform the original reactant at lower temperatures.