Which statement correctly describes an exothermic reaction at equilibrium?

A correctly described exothermic reaction at equilibrium indicates that heat is released during the reaction. When an exothermic reaction reaches equilibrium, if the temperature decreases, the system will respond by favoring the formation of more products to generate additional heat. This is in line with Le Chatelier's principle, which states that if a change is made to a system at equilibrium, the system will adjust to counteract that change.

In an exothermic reaction, if the temperature is reduced, more products will shift to the left (favoring product formation) to replace the heat that is lost, leading to an increase in the concentration of the products. Therefore, option C accurately describes the behavior of an exothermic reaction at equilibrium in response to a decrease in temperature.