Apply Le Chatelier's principle to predict the direction of a reaction when the concentration of a reactant is increased.

• A. The reaction will shift towards the products to restore equilibrium.
• B. The reaction will remain unchanged as equilibrium is not affected by concentration changes.
• C. The reaction will shift towards the side with fewer moles of gas.
• D. The reaction will shift towards the reactants to restore equilibrium.

Answer: (A)