Which of the following statements are contradictory of each other?

1.All human beings are mortal

2.Some human beings are not mortal

3.Some human beings are mortal

4.No human beings are mortal

A2 & 4 only

B2 & 3 only

C1 & 4 only

D1 & 2 only ✓ Correct

Correct answer: (D) 1 & 2 only

Explanation

Statement 1 and Statement 2 are exact contradictories with always-opposite truth values.

Statement 1 is the universal affirmative A: All human beings are mortal.

Statement 2 is the particular negative O: Some human beings are not mortal.

An A and its matching O deny each other precisely, one true only if the other is false.

This mutual exclusion and exhaustion is the contradictory relation.

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