Which of the following statements best defines Le Châtelier's principle?
A. It can be used to predict the effect of applying conditions of equilibrium on a chemical system.
B. It can be used to predict the effect of applying conditions of stress on a chemical system that is at equilibrium.
C. It can be used to predict the effect of increasing the reaction rate of a chemical system that is at equilibrium.
D. It can be used to predict the effect of a catalyst on a chemical system that is at equilibrium.