A given nitrogen-containing aromatic compound A reacts with Sn / HCl, followed by HNO_2 to give an unstable compound B. B, on treatment with phenol,…

A given nitrogen-containing aromatic compound $\displaystyle A$ reacts with $\displaystyle \mathrm{Sn} / \mathrm{HCl}$, followed by $\displaystyle \mathrm{HNO}_2$ to give an unstable compound $\displaystyle B$. $\displaystyle B$, on treatment with phenol, forms a beautiful coloured compound $\displaystyle C$ with the molecular formula $\displaystyle \mathrm{C}_{12} \mathrm{H}_{10} \mathrm{~N}_2 \mathrm{O}$. The structure of compound $\displaystyle A$ is