For the Reaction a + B $\rightarrow$ C + D,the Equilibrium Constant (Keq)is Defined as
A)[A][B]/[C][D]

For the reaction A + B $\rightarrow$ C + D,the equilibrium constant (Keq) is defined as

A) [A][B]/[C][D].
B) [C][D]/[A][B].
C) [A][D]/[B][C].
D) [B][C]/[A][D].