The answer is: B
Explanation
The correct option is B: Explanation IV to Section 11.
Constructive res judicata is a sub-set of the doctrine of res judicata, which means that a matter that could have been raised and decided in a previous suit, but was not, cannot be raised in a subsequent suit between the same parties. Explanation IV to Section 11 of the Code of Civil Procedure states that "Any matter which might and ought to have been made ground of defence or attack in such former suit shall be deemed to have been a matter directly and substantially in issue in such suit." This means that if a party fails to take a plea that was available to him in a suit, he cannot take that plea in a later suit arising from the same cause of action. The object of constructive res judicata is to compel the parties to bring forward their whole case in one suit and to prevent them from splitting their claims or defences. This ensures the finality of judgments and avoids multiplicity of litigation.