Which of the following factors would affect the equilibrium constant?

Explanation

Equilibrium constants aren't changed if you change the concentrations of things present in the equilibrium. The only thing that changes an equilibrium constant is a change of temperature. Yes, temperature is the only factor that affects the value of an equilibrium constant; changes in concentration or pressure do not change the equilibrium constant, only the position of the equilibrium itself, as explained by Le Chatelier's principle.