The hospital's roster classification rule states: “All registered nurses are licensed medical personnel.” While checking the system, an administrator sees: “Xiao Lin is licensed medical personnel.” Badge production costs went up this month. The supervisor then says: “Therefore, Xiao Lin is a registered nurse.” What is wrong with this judgment?

Answer: B

• AThe reasoning is valid: if everyone in this category has that qualification, then anyone with the qualification naturally belongs to this category.✗ This mistakenly treats a one-way classification rule as if it could be applied in reverse.
• BMore than one category carries this qualification, so his occupational category cannot be determined from it.✓ Correct. The same qualification can be held by multiple occupational categories; sharing a qualification does not prove sharing a category. The middle term is undistributed.
• CThe problem is that the universal claim in the hospital's rule is itself false, so it cannot be used for judgment.✗ This is wrong because the hospital's rule can well be true; the real issue lies not in the rule's truth but in the reversed classification.
• DThe problem is that the system's data source is too limited; the verification sample should be expanded before judging.✗ This is wrong because the data source and sample size have no bearing on whether the occupational category can be inferred from these two pieces of information.