If the statement Some trucks are not polluting vehicles is given as false, then which of the following statements can be immediately inferred to be true?
1.All trucks are non-polluting vehicles.
2.All trucks are polluting vehicles.
3.Some trucks are polluting vehicles.
4.All polluting vehicles are trucks.
A1 & 3 only
B3 & 4 only
C2, 3 & 4 only
D2 & 3 only ✓ Correct
Correct answer: (D) 2 & 3 only
Explanation
Statements 2 and 3 can be inferred true.
The given false proposition is the O form, some trucks are not polluting vehicles.
The contradictory of O is the A form, so all trucks are polluting vehicles is true (Statement 2).
From a true A its subaltern I follows, so some trucks are polluting vehicles is true (Statement 3).
Falsity of the O forces its contradictory A, which in turn yields its subaltern I.
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