The company confidentiality policy states: “All top-secret documents are encrypted documents.” During an audit, the system shows: “This contract is an encrypted document.” Seeing this, Xiao Lin says: “Therefore, this contract is a top-secret document.” What is wrong with this reasoning?

Answer: A

• AEncrypted documents are not limited to top-secret documents, so the fact that the contract is encrypted does not prove it belongs to that classification.✓ Correct. The policy only says documents of that classification must be encrypted; it does not say all encrypted documents belong to that classification. This is the fallacy of the undistributed middle.
• BThe reasoning is valid: since all documents of that classification are encrypted, the contract, being encrypted, naturally belongs to that classification.✗ Wrong. This reverses the direction of the policy's rule; sharing one feature does not automatically place something in that category.
• CThe problem is that the policy's rule itself is invalid, so the conclusion has no basis.✗ Wrong. The policy in the question is a given rule; the issue is not whether the rule itself holds.
• DThe problem is that only one contract was checked, and the sample is too small; several more should be checked.✗ Wrong. This misidentifies the issue as sampling size, which has no bearing on whether this contract can be classified in that category.