During a design review, the art teacher had earlier reminded everyone: “If what is drawn is a square, then what is drawn is a quadrilateral.” After Xiaolin uploaded his sketch, the image recognition system indicated: what is drawn is a quadrilateral. He immediately said: “So what is drawn is a square.” Can this conclusion be validly drawn from what was said?

Answer: C

• AThe reasoning holds, because a square is by definition a quadrilateral, and the system's result confirms exactly that.✗ It is true that every square is a quadrilateral, but the converse does not follow: a quadrilateral need not be a square. This option mistakes confirmation of the consequent for valid inference.
• BThe reasoning is flawed, because it commits the error of inferring “if it is not a square, then it is not a quadrilateral.”✗ That error (denying the antecedent) is a real one, but Xiaolin did not reason from “not a square” to “not a quadrilateral,” so this mischaracterizes his actual mistake.
• CThe conclusion does not follow: the drawing could also be a rectangle, a trapezoid, or some other quadrilateral, so it need not be a square.✓ There are many kinds of quadrilateral the system could have detected, so this single result alone cannot establish that the drawing is a square. This correctly identifies the fallacy of affirming the consequent.
• DThe reasoning is flawed, because the image recognition system may lack sufficient resolution and its detection data may be inaccurate.✗ This merely questions the reliability of the system's data; it never addresses whether the conclusion could be drawn even if the data were perfectly accurate.