If the statement 'Some animals are not birds' is given as false, which of the following statements can be inferred to be true?

1.All animals are birds.

2.No birds are animals.

3.No animals are birds.

4.Some animals are birds.

A1 & 2 only

B2 & 4 only

C1 & 4 only ✓ Correct

D2 & 3 only

Correct answer: (C) 1 & 4 only

Explanation

Given 'Some animals are not birds' is false, its contradictory 'All animals are birds' must be true.

That true universal affirmative is Statement 1.

By subalternation, a true universal affirmative makes the particular 'Some animals are birds' true, which is Statement 4.

Statement 3, 'No animals are birds', is the contrary and must be false when the universal affirmative is true.

Statement 2, 'No birds are animals', is not guaranteed and cannot be inferred true.

Hence the certain truths are the first and the fourth.

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