What is the equilibrium constant for the reaction A + B ⇌ C + D?

A. [C][D]/[A][B]
B. [A][B]/[C][D]
C. [C]^2[D]/[A]^2[B]
D. [D]/[C][A][B]

Answer: [C][D]/[A][B]


Additional Information: The equilibrium constant expression is the product of the concentrations of the products divided by the reactants.