Consider the following equilibrium expression, \mathbf{K}=\frac{[\mathbf{Y}][\mathbf{Z}]^{3}}{[X][W]^{2}} The equation of the forward reaction for this equilibrium expression is \begin{array}{ll} \text { A. } & Y+Z_{3} \quad \rightleftharpoons W_{2}+X \end{array} \text {

B. } \quad W_{2}+X \quad \rightleftharpoons \quad Y+Z^{3} \text { C. } \quad Y+3 Z \quad \rightleftharpoons \quad 2 W+X \text { D. } 2 W+X \quad \rightleftharpoons \quad Y+3 Z