Answer: The correct statement is the concentrations change to maintain the original value of K.
Step-by-step explanation:
According to the Le-Chatlier's principle, if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect and to maintain the original value of equilibrium constant.
If the concentration of reactants are increased, the equilibrium will shift in the forward direction to decrease the concentration of reactants and if the concentration of reactants are decreased, the equilibrium will shift in the backward direction to decrease the concentration of products.
Hence, the correct statement is the concentrations change to maintain the original value of K.