Which among the following compounds has the highest melting point?

Regarding the solubility of $p$-nitrophenol and salicylaldehyde in a base:

Identify the product $P$ obtained in the following reaction: $C_6H_5OH + HCHO \xrightarrow{\text{Acid}} P$

Write the equations involved in the following reactions:
$(i)$ Reimer-Tiemann reaction
$(ii)$ Kolbe's reaction

The major product of the following reaction is

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: