K=\frac{[C]^{2}[D]^{2}}{[A]^{4}[B]} is the formulation of the chemical equilibrium constant equation for which of the following reactions? \text { (a) } \mathbf{C}_{2}+\mathbf{D}_{2} \leftrightarrow \mathbf{A}_{4}+\mathrm{B} ; \text { (b) } \mathbf{4} \mathbf{A}+\mathbf{B} \leftrightarrow \mathbf{2 C}+\mathbf{2 D} ;(\mathbf{c}) \mathbf{4 C}+\mathbf{2 D} \leftrightarrow \mathbf{2 A}+\mathbf{B} ;(\mathbf{d}) \mathbf{A}_{4}+\mathbf{B} +C2 +D2

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