For a reaction scheme $\mathrm{A}\stackrel{{\mathrm{k}}_1}{⟶}\mathrm{B}\stackrel{{\mathrm{k}}_2}{⟶}\mathrm{C}$, if the rate of formation of B is set to be zero then the concentration of B is given by

$$\begin{gathered} \text{ Solution:- (A) }\left(\frac{{\mathrm{k}}_1}{{\mathrm{k}}_2}\right)\left[\mathrm{A}\right] \\ \mathrm{A}\stackrel{{\mathrm{k}}_1}{⟶}\mathrm{B}\stackrel{{\mathrm{k}}_2}{⟶}\mathrm{C} \\ \text{ According to given question, } \\ \begin{array}{rl} & \frac{\mathrm{d}\left[\mathrm{B}\right]}{\mathrm{dt}}=0={\mathrm{K}}_1\left[\mathrm{A}\right]-{\mathrm{K}}_2\left[\mathrm{B}\right]\\ & \Rightarrow \left[\mathrm{B}\right]=\frac{{\mathrm{K}}_1}{{\mathrm{K}}_2}\left[\mathrm{A}\right]\end{array} \end{gathered}$$

Therefore, the correct option is (C).