A compound $\left(\mathrm{A}\right)$ when treated with ${\mathrm{PCl}}_5$ and then ammonia gave $\left(\mathrm{B}\right).$ $\left(\mathrm{B}\right)$ when treated with bromine and caustic potash produced $\left(\mathrm{C}\right).$ $\left(\mathrm{C}\right)$ on treatment with ${\mathrm{NaNO}}_2$ and $\mathrm{HCl}$ at $0^{°}\mathrm{C}$ and then boiling produce ortho-cresol. Compound $\left(\mathrm{A}\right)$ is: