Statements: (a) All books are boxes. (b) All boxes are pens. (c) All pens are papers. Conclusions: I. Some papers are books. II. All books are papers. III. Some pens are books. IV. All boxes are books.

All the three statements are Universal Affirmative (A-type).
All books are boxes. ↔ All boxes are pens.
A + A ⇒ A-type of Conclusion "All books are pens."
Conclusion III is Converse of it.
All books are pens. ↔All pens are papers.
A + A ⇒ A-type of Conclusion "All books are papers."
This is Conclusion II.
Conclusion I is Converse of it.
All boxes are pens. ↔ All pens are papers.
A + A ⇒ A-type of Conclusion "All boxes are papers."