All pens are pencils. All pencils are erasers. Which conclusion follows?
- A. All erasers are pens
- B. All pens are erasers
- C. Some erasers are not pencils
- D. No pen is an eraser
Explanation
The two statements chain together, so everything in the pen category is inside pencils and therefore inside erasers. Reversing the chain to say all erasers are pens is invalid, since the outer category may contain much more. Drawing three nested circles settles the question immediately.
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