If one of two sub-contraries is true, then the other one is

ATrue

BFalse

CDoubtful ✓ Correct

DNeither true nor false

Correct answer: (C) Doubtful

Explanation

If one of two sub-contraries is true, the other is doubtful.

Sub-contraries can both be true at the same time.

So truth of one does not settle the other's value.

If "Some S are P" is true, "Some S are not P" may be true or false.

This undetermined value of the second is what "doubtful" names.

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