If the statement 'All tigers are mammals' is given as true, then which of the following statements could be immediately inferred to be false?

1.Some tigers are not mammals

2.Some tigers are mammals

3.No tigers are mammals

4.Some mammals are tigers

A1 & 4 only

B1, 2 & 4 only

C1 & 3 only ✓ Correct

D2 & 4 only

Correct answer: (C) 1 & 3 only

Explanation

Statements 1 and 3 can be inferred false.

The given "All tigers are mammals" is an A proposition, taken true.

Its contradictory, the O "Some tigers are not mammals" (1), is therefore false.

Its contrary, the E "No tigers are mammals" (3), is also false.

Statements 2 and 4 stay true by subalternation and conversion, so only 1 and 3 fail.

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