Which of the following statements are logically equivalent?

1.No aeroplanes are electric vehicles

2.All non-electric vehicles are non-aeroplanes

3.No electric vehicles are aeroplanes

4.All aeroplanes are non-electric vehicles

A2, 3 & 4 only

B1, 3 & 4 only ✓ Correct

C1 & 2 only

D2 & 4 only

Correct answer: (B) 1, 3 & 4 only

Explanation

Statements 1, 3 and 4 are logically equivalent.

Take 1, the E proposition "No aeroplanes are electric vehicles".

Its conversion gives 3, "No electric vehicles are aeroplanes".

Its obversion gives 4, "All aeroplanes are non-electric vehicles".

Statement 2 asserts All non-E are non-A, which reduces to All A are E and clashes.

Conversion and obversion preserve meaning, binding 1, 3 and 4 together.

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