Which of the following statements contradict each other?

1.All ducks are birds.

2.Some ducks are birds.

3.Some ducks are not birds.

4.No ducks are birds.

A1 & 4 only

B2 & 3 only

C2 & 4 only ✓ Correct

D3 & 4 only

Correct answer: (C) 2 & 4 only

Explanation

Statements 2 and 4 contradict each other.

Statement 2, 'Some ducks are birds', is a particular affirmative.

Statement 4, 'No ducks are birds', is the universal negative on the same terms.

A particular affirmative and a universal negative are contradictories, so one must be true and the other false.

Statements 1 and 3 form the other contradictory pair, while 2 and 3 are only subcontraries.

Hence the contradicting pair asked for is the second and the fourth.

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