Question

L is the only son of A and S. S has one sibling, B, who is married to L's aunt, K. B is the only son of D. How are L and D related? Select the possible option(s):

• A. Grandchild and Paternal Grandfather
• B. Grandchild and Maternal Grandfather
• C. Grandchild and Paternal Grandmother
• D. Grandchild and Maternal Grandmother

Hint:

When you see "only son/daughter," use it to fix genders and sides of the family. Here "B is the only son of D" forces S to be female, putting D on the maternal side.

Answer 1

The Correct Option is B, D

Step 1: Decode the family links.
L is the only son of parents A and S $\Rightarrow$ L is male; A and S are L's parents (genders not yet known).
S has one sibling, B.
B is married to L's aunt K. If K were S's sister, B (S's sibling) would be marrying his own sister — impossible. Hence K is A's sister (paternal aunt of L). Therefore, B is S's only sibling and A's brother-in-law.

Step 2: Use "B is the only son of D".
Since S and B are siblings and B is the only son of D, it follows that: - B is male, - S cannot be male (otherwise D would have at least two sons, contradicting "only son").
Therefore, S is female $\Rightarrow$ S is L's mother. Consequently, D is a parent of S, i.e., D is L's maternal grandparent.

Step 3: Determine which options fit.
From Step 2, the relationship between L and D is always "grandchild $\leftrightarrow$ maternal grandparent". The question does not specify D's gender. Hence both of the following are possible and consistent with the data: \[ \text{(B) Grandchild and \underline{Maternal Grandfather}}, \text{(D) Grandchild and \underline{Maternal Grandmother}}. \] Why not paternal?
If D were on the paternal side, D would be a parent of A. But D is explicitly the parent of B, who is S's only sibling; thus D is on S's side, not A's. So (A) and (C) are impossible.