Concept:
In Sanskrit and Hindi morphology, a उपसर्ग (prefix) is a meaningful element added before a root word to modify its meaning. The prefix “ अनु” generally conveys meanings such as following, after, or along.
To solve this question, each word must be broken down morphologically.
Step 1: Analysis of (A) अन्वेषण
\[
{\hindifont अनु} + {\hindifont एषण} = {\hindifont अन्वेषण}
\]
Here, the prefix अनु is clearly present.
Step 2: Analysis of (B) अनुपम
\[
{\hindifont अन्} + {\hindifont उपम} = {\hindifont अनुपम}
\]
Here, the prefix is not “ अनु” but “ अन्”, which is a negative prefix meaning “without” or “not”.
Hence, this word does NOT contain the prefix अनु.
Step 3: Analysis of (C) अनुचर
\[
{\hindifont अनु} + {\hindifont चर} = {\hindifont अनुचर}
\]
Clearly formed using the prefix “ अनु”.
Step 4: Analysis of (D) अनुराग
\[
{\hindifont अनु} + {\hindifont राग} = {\hindifont अनुराग}
\]
Also formed using the prefix “ अनु”.
Final conclusion:
Only अनुपम is formed using the prefix “ अन्”, not “ अनु”.
Therefore, Option (B) is correct.