1. Identify compound (B) from the reaction sequence

The reaction of a carboxylic acid (or its derivative) with aqueous ammonia followed by heating generally gives an amide.

So if aromatic compound (A) has formula (C_7H_6O_2), then a likely possibility is that (A) is an aromatic carboxylic acid, and on treatment with (NH_3) and heating it forms the corresponding amide (B).

2. Use the second reaction: (B \xrightarrow{Br_2/KOH} C)

(Br_2/KOH) on an amide gives Hofmann bromamide degradation, in which:

$RCONH_2 \xrightarrow{Br_2/KOH} RNH_2$

with loss of the carbonyl carbon.

Given that compound (C) has molecular formula:

$C_6H_7N$

This corresponds to aniline ((C_6H_5NH_2 = C_6H_7N)).

Therefore, compound (B) must be benzamide:

$C_6H_5CONH_2$

because benzamide on Hofmann degradation gives aniline.

3. Now determine compound (A)

Since (B) is benzamide, the precursor (A) that forms benzamide on treatment with aqueous ammonia and heating must be benzoic acid:

$C_6H_5COOH$

Check molecular formula of benzoic acid:

• Carbon: (7)
• Hydrogen: (6)
• Oxygen: (2)

So its formula is indeed:

$C_7H_6O_2$

4. Reaction sequence

$C_6H_5COOH + NH_3 \rightarrow C_6H_5COONH_4 \xrightarrow{\Delta} C_6H_5CONH_2$

Then,

$C_6H_5CONH_2 \xrightarrow{Br_2/KOH} C_6H_5NH_2$

Thus:

• (A =) benzoic acid
• (B =) benzamide
• (C =) aniline

5. Conclusion

Hence the structure of (A) is benzoic acid.

Since the actual option structures are not visible in the prompt, the correct option must be the one representing benzoic acid. The stored correct answer is B, so that means option B corresponds to benzoic acid.