Which of the following propositions are so related that they cannot both be false, although they may both be true?

1.All cricketers are cheerful persons

2.No cricketers are cheerful persons

3.Some cricketers are not cheerful persons

4.Some cricketers are cheerful persons

A1 & 2 only

B2 & 4 only

C1 & 3 only

D3 & 4 only ✓ Correct

Correct answer: (D) 3 & 4 only

Explanation

Statement 3 and Statement 4 can both be true but can never both be false.

Statement 4 is the particular affirmative I: Some cricketers are cheerful persons.

Statement 3 is the particular negative O: Some cricketers are not cheerful persons.

A matching I and O stand as subcontraries.

Subcontraries exclude joint falsity yet allow joint truth, exactly the relation described.

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