An organic compound $\left(\mathrm{A}\right)$ composed of $\mathrm{C}, \mathrm{H}$ and $\mathrm{O}$ gives characteristic colour with ceric ammonium nitrate. Treatement of $\left(\mathrm{A}\right)$ with ${\mathrm{PCl}}_5$ gives $\left(\mathrm{B}\right)$, which reacts with $\mathrm{KCN}$ to form $\left(\mathrm{C}\right)$. The reduction of $\left(\mathrm{C}\right)$ with warm $\mathrm{Na}/{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$ produces $\left(\mathrm{D}\right).$ which on heating gives $\left(\mathrm{E}\right)$ with evolution of ammonia. Pyridine is obtained on treatment of $\left(\mathrm{E}\right)$ with nitrobenzene. Give structure of compounds $\left(\mathrm{A}\right)$ to $\left(\mathrm{E}\right)$ with proper reasoning.