How is M related to N? Statements: I. B is the daughter of M and sister of Q.…

Concept: In a data-sufficiency question, test each statement alone against what the question asks, then test the two together, before declaring a relationship 'determined'. A relationship is genuinely determined only when every family configuration consistent with the given facts forces the same single answer - if even one alternative configuration also fits the facts, the relationship is not determined.

1. Statement I alone: B is the daughter of M, so M is a parent of B (M's own gender is never stated). Statement I never mentions K or N, so it says nothing about N - Statement I alone is not sufficient.

2. Statement II alone: N is the son of K, and K is B's grandfather, so N is a child of one of B's parents' parents. Statement II never mentions M, so it says nothing about M - Statement II alone is not sufficient.

3. Combine I and II: From I, M is a parent of B. From II, K is B's grandfather, i.e. K is the parent of one of B's two parents. Nothing in either statement says whether K is specifically M's parent or the parent of B's other, unnamed parent - both are equally consistent with the facts given.

4. If K is M's own parent, N (K's son) is a sibling of M. If K is the parent of B's other parent instead, N is unrelated to M by blood. Since both configurations remain valid together, the two statements combined still do not fix a single relationship between M and N.

Cross-check: Testing both assignments of K (as M's parent, or as the parent of B's other parent) against every stated fact shows each one holds up equally well - confirming that neither statement alone, nor the two together, pin down how M and N are related.