Which of the following statements are logically equivalent? Choose the correct answer from the options given below.

1.All cows are herbivores.

2.All herbivores are cows.

3.Some herbivores are cows.

4.No cows are non-herbivores.

A1, 2 only

B2, 4 only

C2, 3 only

D1, 4 only ✓ Correct

Correct answer: (D) 1, 4 only

Explanation

Two propositions are equivalent: "All cows are herbivores" and "No cows are non-herbivores".

Statement 1 is the universal affirmative A.

Statement 4 is the obverse of A, formed by making it negative and negating the predicate.

Obversion keeps the meaning unchanged, so Statement 4 says the same as Statement 1.

The converse and the converse by limitation do not preserve the force of an A proposition.

Obversion being truth-preserving makes Statements 1 and 4 logically equivalent.

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