Step 1: Nature of exploratory research.
Exploratory research is unstructured, flexible, and adaptable — designed to generate insights and ideas rather than test hypotheses.
Step 2: Why option (b) is wrong.
Pre-planned and structured designs are characteristics of conclusive research, not exploratory. Hence, calling exploratory research “pre-planned and structured” is incorrect.
Step 3: Verification of other options.
- (a) Flexible — correct for exploratory research.
- (c) Versatile — correct because it can be used in various situations.
- (d) Often the front end — correct because it precedes detailed, structured studies.
\[
\boxed{(b)}
\]