Is D the mother of S? I. L is the husband of D and has exactly three children. II. N is the brother of S and P. P is the daughter of L.

Introduction / Context:
We must deduce whether D is S’s mother from family relations.

Given Data / Assumptions:

• I: L is D’s husband; L has exactly three children.
• II: N is brother of S and P; P is L’s daughter.
• Standard puzzle convention: “brother/daughter” imply biological child unless otherwise stated.

Concept / Approach:
Combine sibling info with the fixed count of L’s children and the marriage of L and D.

Step-by-Step Reasoning:
From II: N, S, P are siblings (N is brother of both S and P). Also P is child of L ⇒ N and S are (typically) children of L as well.From I: L has exactly three children ⇒ the set of L’s children is {N, S, P}.Since L is married to D, and no alternative mother is indicated, D is the mother of L’s children under the usual assumption.

Why Other Options Are Wrong:
I alone gives no link to S; II alone gives no link to D; both are needed to tie S to L and then to D.

Common Pitfalls:
Allowing step/adoptive exceptions without textual support; DS uses minimal standard assumptions.

Final Answer:
Both statements together are necessary.