An organic compound [A] having molecular formula gives a characteristic colour with aqueous…

An organic compound [A] having molecular formula $\text{C}_6\text{H}_6\text{O}$ gives a characteristic colour with aqueous $\text{FeCl}_3$ solution. [A] on treatment with $\text{CO}_2$ and $\text{NaOH}$ at $400\text{ K}$ under pressure gives [B] which on acidification gives compound [C]. [C] reacts with acetyl chloride to give [D] which is a popular pain killer. Identify the compounds [A], [B], [C] and [D].