Step 1: Understanding the Figure:
The figure shows a benzene ring with a \(-\text{COOH}\) group on one carbon and a \(-\text{CH}_3\) group on the neighbouring (adjacent) ring carbon.
Step 2: Key Rule:
In IUPAC naming, the carboxylic acid is the principal functional group, so the parent is benzoic acid. The ring carbon bearing \(-\text{COOH}\) is numbered 1, and the substituent gets the lowest possible locant.
Step 3: Detailed Explanation:
The methyl group is on the carbon next to C-1, so it takes locant 2. The name is therefore 2-methylbenzoic acid.
Step 4: Why the other options are wrong.
Benzoic acid (A) leaves out the methyl group. 2-Methylcyclohexylcarboxylic acid (D) would have a saturated ring with no double bonds, but the figure shows an aromatic ring. Option (C), o-toluic acid, is the common (trivial) name of the same compound, whereas the question asks for the systematic IUPAC name, which is 2-methylbenzoic acid.
Final Answer:
The IUPAC name is 2-methylbenzoic acid, option (B).
\[ \boxed{\text{2-Methylbenzoic acid (B)}} \]
