An organic compound A $\left(\mathrm{C}_6 \mathrm{H}_6 \mathrm{O}\right)$ gives dark green colouration with ferric chloride. On treatment with $\mathrm{CHCl}_3$ and KOH, followed by acidification gives compound B. Compound B can also be obtained from compound C on reaction with pyridinium chlorochromate (PCC). Identify A, B and C .