As per traditional square of opposition which of the following statements are sub alternate?

A. All plants are oxygen-producers.

B. No plants are oxygen producers.

C. Some plants are not oxygen producers.

D. Some plants are oxygen-producers.

Choose the correct answer from the options given below:

The correct answer is B and C only.
Key Points

• As per the traditional square of opposition, subalternate propositions are a pair of propositions where one proposition is the subaltern of the other.

The subaltern proposition is the proposition that is logically weaker and more specific than the superaltern proposition. In other words, if the superaltern proposition is true, then the subaltern proposition must also be true, but the reverse is not necessarily true.

• In this case, the superaltern proposition is B: "No plants are oxygen producers", which is a universal negative proposition. The subaltern proposition is C: "Some plants are not oxygen producers", which is a particular negative proposition.

If the superaltern proposition B is true, then the subaltern proposition C must also be true, because if no plants are oxygen producers, then it follows logically that some plants are not oxygen producers.

• On the other hand, propositions A and D are not subalternate to proposition B. Proposition A is a universal affirmative proposition, which asserts that all plants are oxygen-producers.

Proposition D is a particular affirmative proposition, which asserts that some plants are oxygen-producers. These propositions do not logically follow from proposition B, and proposition B does not logically follow from them.

Therefore, the correct answer is B and C, because proposition B is the superaltern proposition and proposition C is the subaltern proposition