Syllogism — Premises: (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.

Introduction / Context:
We have a chain of three universal inclusions. We must test a mix of universal and existential conclusions.

Given Data / Assumptions:

• Books ⊆ Boxes.
• Boxes ⊆ Pens.
• Pens ⊆ Papers.
• Non-emptiness of Books for existential claims common in such tests.

Concept / Approach:
By transitivity, Books ⊆ Papers (II). Therefore, if any book exists, it is a paper, validating I. Also, Books ⊆ Pens, so some pens are books (III) under non-emptiness. IV (All boxes are books) reverses inclusion and is invalid.

Step-by-Step Solution:

Verification / Alternative check:
A concrete chain example quickly confirms I, II, III while falsifying IV by allowing boxes that are not books.

Why Other Options Are Wrong:
Any option denying any of I–III or asserting IV conflicts with the chain.

Common Pitfalls:
Overlooking that existential conclusions require at least one member, typically assumed in exam problems.

Final Answer:
Only conclusions I, II and III follow.