For which of the following forms of categorical propositions contraposition is valid?
A. Some S is P
B. Some S is not P
C. No S is P
D. All S is P
Choose the correct answer from the options given below:

Correct option is D

Contraposition is valid for certain types of categorical propositions where the quality of the statement (affirmative or negative) is reversed and the subject and predicate are interchanged, followed by negating both. The forms where contraposition is valid include:
· No S is P (E form): By contraposition, "No P is S."
· All S is P (A form): By contraposition, "All non-P is non-S."
· Some S is not P (O form): By contraposition, "Some non-P is not non-S." For the "Some S is P" (I form), contraposition is not valid. Hence, options B, C, and D are correct.
Information Booster:
· A: Some S is P – This is a particular affirmative (I form), and contraposition is not valid for this form.
· B: Some S is not P – This is a particular negative (O form), and contraposition is valid.
· C: No S is P – This is a universal negative (E form), and contraposition is valid.
· D: All S is P – This is a universal affirmative (A form), and contraposition is valid but requires additional steps (double negation).