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

1.Some non-intelligent animals are non-apes

2.Some apes are not intelligent animals

3.Some apes are non-intelligent animals

4.Some non-intelligent animals are not non-apes

A1, 2 and 3 only

B1 and 3 only

C1 and 4 only

D2, 3 and 4 only ✓ Correct

Correct answer: (D) 2, 3 and 4 only

Explanation

Statements 2, 3 and 4 all say the same thing about apes and intelligent animals.

Statement 2 is 'Some apes are not intelligent animals', an O proposition.

Statement 3 obverts it to 'Some apes are non-intelligent animals', keeping the truth value.

Statement 4, 'Some non-intelligent animals are not non-apes', is its contrapositive.

Obversion and contraposition are valid on the O form, so the three coincide.

The remaining particular affirmative about non-apes does not share this equivalence.

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