Preposition choice with "difference": Choose the correct preposition. Original sentence: "They examined both the samples very carefully but failed to detect any difference in them." Select the best correction.

Given data

• Exactly two items: "both the samples".

Concept/Approach
Use between for comparison/contrast of two items; use among for three or more. The determiner "any" fits non-affirmative contexts after "failed to".

Step-by-step
Replace "difference in them" with "difference between them".

Option analysis
C is correct. A/B have determiner mismatch or weaker quantification; D misuses "among"; E leaves the error.

Final Answer
any difference between