If the statement 'All trucks are polluting vehicles' is given as true, which of the following statements could be immediately inferred to be false? Choose the correct answer from the options given below.

1.Some trucks are polluting vehicles

2.Some polluting vehicles are trucks

3.Some trucks are not polluting vehicles

4.No trucks are polluting vehicles

A3 and 4 only ✓ Correct

B1 and 2 only

C2 and 3 only

D1 and 3 only

Correct answer: (A) 3 and 4 only

Explanation

Given the universal affirmative as true, its contrary and its contradictory must be false.

'No trucks are polluting vehicles' is the contrary and cannot stand with the true A.

'Some trucks are not polluting vehicles' is the contradictory of A, so it is false.

Meanwhile 'some trucks are' and 'some polluting are trucks' follow validly and stay true.

Thus the two immediately false ones are statements 3 and 4.

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