Statements: • Some tyres are rains. • Some rains are flowers. • All flowers are jungles. • All jungles are tubes. Conclusions: I. Some jungles are tyres. II. Some tubes are rains. III. Some jungles are rains. IV. Some tubes are flowers. Choose the option that must follow.
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AOnly I, II and III follow
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BOnly II, III and IV follow
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COnly I, III and IV follow
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DAll follow
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ENone follows
Answer
Correct Answer: Only II, III and IV follow
Explanation
Introduction / Context:Two universal steps push existence from Flowers onward to Jungles and Tubes. We test which intersections are forced by these inclusions.
Given Data / Assumptions:
- ∃r_f ∈ Rains ∩ Flowers.
- Flowers ⊆ Jungles ⊆ Tubes.
- ∃t_r ∈ Tyres ∩ Rains (may be different from r_f).
Concept / Approach:From r_f ∈ Flowers and Flowers ⊆ Jungles, r_f ∈ Jungles. Hence Jungles ∩ Rains ≠ ∅ (III). Also, since Jungles ⊆ Tubes, r_f ∈ Tubes, so Tubes ∩ Rains ≠ ∅ (II) and Tubes ∩ Flowers ≠ ∅ (IV). There is no forced link between Tyres and Jungles, so I is not necessary.
Step-by-Step Solution:1) Push r_f through universals: Flowers → Jungles → Tubes.2) Record intersections: Jungles ∩ Rains (III), Tubes ∩ Rains (II), and Tubes ∩ Flowers (IV) are all guaranteed.3) For I, we would need the Tyres∩Rains witness to be the same as the Rains∩Flowers witness; not required.
Verification / Alternative check:Model Tyres∩Rains disjoint from Flowers. Then II–IV still hold via the flower-rain element, while I fails.
Why Other Options Are Wrong:They include I, which is not forced.
Common Pitfalls:Equating different “some” witnesses.
Final Answer:Only II, III and IV follow.