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

1. A
   $\text{Benzamide}$
2. B
   $\text{Benzonitrile}$
3. C
   $\text{Nitrobenzene}$
4. D
   $\text{Phenyl isocyanide}$