Modus tollens is the valid rule that allows us to infer the negation of the antecedent from a conditional and the negation of its consequent. In symbolic form, from P → Q and ¬Q we conclude ¬P. This pattern preserves validity, because if P had been true, Q would have had to be true as well, so the falsity of Q forces the falsity of P.
Option A:
Option A is modus ponens, which affirms the antecedent to derive the consequent, a different valid pattern.
Option B:
Option B commits the fallacy of denying the antecedent, which is not generally valid.
Option C:
Option C correctly captures the modus tollens form, using the falsity of the consequent to infer the falsity of the antecedent.
Option D:
Option D is the fallacy of affirming the consequent, which is invalid in general.
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