Product (A) is:

The correct answer is option 2. \(C_6H_5OH\).

To identify the product \(A\) of the given reaction sequence, we need to understand each step:

Given Reaction Sequence:

\(C_6H_5NO_2 \underset{\underset{3. H_2O}{2. HNO_2}}{\overset{1. Fe/HCl}{\longrightarrow}} A\))

Here is how to interpret each step

Reduction with Fe/HCl:

The nitro group (\(-NO_2\)) in \(C_6H_5NO_2\) (nitrobenzene) is reduced to an amine group (\(-NH_2\)) using iron and hydrochloric acid. This step converts nitrobenzene to aniline (\(C_6H_5NH_2\)).

Diazotization with \(HNO_2\) (Nitrous acid):

Aniline (\(C_6H_5NH_2\)) is treated with nitrous acid (\(HNO_2\)) at a low temperature (0–5°C) to form a diazonium salt. The diazotization of aniline produces phenyl diazonium chloride (\(C_6H_5N_2^+ Cl^-\)).

Hydrolysis with \(H_2O\): 

The diazonium salt is hydrolyzed with water, which converts the diazonium group into a hydroxyl group. The hydrolysis of phenyl diazonium chloride results in phenol (\(C_6H_5OH\)).

So, the correct answer is phenol.