Which reagent from the following is used in the Reimer-Tiemann reaction?

What happens when $phenol$ reacts with bromine water?

The reaction is given as: $X \xrightarrow{Y} \text{Benzoquinone}$. Identify $X$ and $Y$ in the above reaction.

Given below are two statements: One is labelled as $Assertion$ $A$ and the other is labelled as $Reason$ $R$:
Assertion $A$: $pK_a$ value of phenol is $10.0$ while that of ethanol is $15.9$.
Reason $R$: Ethanol is a stronger acid than phenol.
In the light of the above statements,choose the correct answer from the options given below:

Product $(A)$ in this reaction is

Which of the following phenols has the largest $pK_a$ value (i.e.,is least acidic)?