Which of the following statements are sub-contraries?

1.All nurses are caring human beings

2.No nurses are caring human beings

3.Some nurses are caring human beings

4.Some nurses are not caring human beings

A1 & 2 only

B1 & 4 only

C2 & 3 only

D3 & 4 only ✓ Correct

Correct answer: (D) 3 & 4 only

Explanation

The sub-contraries are the two particular propositions, I and O.

'Some nurses are caring' is the I proposition (Statement 3).

'Some nurses are not caring' is the O proposition (Statement 4).

Sub-contraries can both be true together but cannot both be false.

The I and O pair on the square of opposition are the sub-contraries.

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