For the reaction given below:

The compound which is not formed as a product in the reaction is a:

The reactant $$\mathrm{4\text{-}(Hydroxymethyl)benzaldehyde}$$ contains an aldehyde group without:

$$\mathrm{\alpha\text{-}Hydrogens}$$

Hence, in presence of $$\mathrm{NaOH}$$ and heat, it undergoes the:

$$\mathrm{Cannizzaro\ Reaction}$$

In this reaction, one molecule undergoes oxidation while another undergoes reduction.

The aldehyde group $$\mathrm{(-CHO)}$$ of one molecule is oxidised into:

$$\mathrm{(-COOH)}$$

forming:

$$\mathrm{4\text{-}(Hydroxymethyl)benzoic\ Acid}$$

The original hydroxymethyl group $$\mathrm{(-CH_2OH)}$$ remains unaffected.

The aldehyde group of another molecule is reduced into:

$$\mathrm{(-CH_2OH)}$$

forming:

$$\mathrm{1,4\text{-}Benzenedimethanol}$$

Thus, the products formed contain:

$$\mathrm{Monocarboxylic\ Acid}$$

and

$$\mathrm{Diol}$$

No product containing two carboxylic acid groups is formed.

Correct Option: $$\mathrm{D}$$