Difficulty: Easy
Correct Answer: None follows
Explanation:
Introduction / Context:
This question blends an existential overlap with a universal negative and a universal inclusion. The aim is to see whether any necessary relationship can be forced between brushes and rats or between towels and soaps.
Given Data / Assumptions:
Concept / Approach:
No B is S tells us brushes and soaps are disjoint. All S are R only places soaps inside rats; it does not say all rats are soaps. Therefore, brushes might still be rats (if there exist rats outside S) or might not be; the premises are silent. Also, nothing connects towels to soaps except through brushes, and brushes are explicitly not soaps.
Step-by-Step Solution:
Verification / Alternative check:
Model A: Let S ⊆ R and R also contain r1 not in S. Let B = {r1} and some T include r1. Then I is true and II is false. Model B: Let B disjoint from R entirely, and T overlap B. Then II is true and I false. Since different valid models yield different truth values, none of I–III is necessary.
Why Other Options Are Wrong:
Common Pitfalls:
Assuming all rats are soaps (converse of all S are R); trying to pass through the brush set to reach soaps despite the explicit exclusion.
Final Answer:
None follows
Discussion & Comments