Choose the correct diagram which shows/represents the arguments correctly.
No fish are birds
All pens are fish
No pens are birds
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) →
In a Venn diagram, “All X are Y” puts circle X wholly inside circle Y, and “No X are Y” keeps the two circles apart.
All pens are fish: the Pens circle lies inside the Fish circle
No fish are birds: the Birds circle stays outside the Fish circle
No pens are birds: the pens are inside the fish, so they too stay clear of the birds
Option (3) shows Pens inside Fish, with Birds apart from both.
Why the other options are incorrect
Option (1) — Incorrect. It puts Pens inside Birds, the opposite of “No pens are birds”.
Option (2) — Incorrect. It puts Fish inside Pens (all fish are pens), not pens inside fish.
Option (4) — Incorrect. It keeps Pens apart from Fish, against “All pens are fish”.