Which of the following statement are logically equivalent ?

1.No cars are non-vehicles.

2.Some cars are vehicles.

3.All vehicles are cars.

4.All cars are vehicles.

A2 & 3 only

B2 & 4 only

C1 & 4 only ✓ Correct

D1, 3 & 4 only

Correct answer: (C) 1 & 4 only

Explanation

Statements 1 (No cars are non-vehicles) and 4 (All cars are vehicles) are logically equivalent.

Statement 4 is the universal affirmative all cars are vehicles.

Its obverse changes quality and replaces the predicate by its complement, giving no cars are non-vehicles.

That obverse is exactly Statement 1.

Because obversion preserves truth-value, the two are equivalent.

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