GKFix MCQ Question

What is the general form of the equilibrium constant expression for the reaction A + B ⇌ C + D?

• A. Kc = [A][B]/[C][D]
• B. Kc = [C] + [D]/[A] + [B]
• C. Kc = [C][D]/[A][B]
• D. Kc = [A] + [B]/[C] + [D]