Which of the following statements are logically equivalent?

1.Some dogs are not aggressive animals

2.Some dogs are aggressive animals

3.Some non-dogs are aggressive animals

4.Some non-aggressive animals are not non-dogs

A1, 2 & 3 only

B1 & 3 only

C1 & 4 only ✓ Correct

D2 & 3 only

Correct answer: (C) 1 & 4 only

Explanation

Statements 1 and 4 are logically equivalent.

Statement 1 "Some dogs are not aggressive animals" is an O proposition.

Its contraposition gives "Some non-aggressive animals are not non-dogs".

That is exactly statement 4, so the two carry the same meaning.

Statements 2 and 3 change quantity or terms and do not match.

Contraposition, valid for O, binds statements 1 and 4.

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