A is the son of B. B sister has a son D and a daughter E. F is the maternal uncle of D. How many nephews does F have?

Introduction / Context:
This question combines simple family relations with the specific role of a maternal uncle and then asks for a count of nephews. You need to be clear about who is whose parent and sibling and then see which boys are sons of the sisters of F, because that is what defines nephews in this context.

Given Data / Assumptions:

• A is the son of B.
• B sister has a son D and a daughter E. So D and E are children of B sister.
• F is the maternal uncle of D, which means F is a brother of D mother.
• D mother is B sister.
• We assume that F is a different brother in the same generation as B, not the same person as B, since a new letter is introduced.
• We need to count how many nephews F has, that is, how many male children belong to F sisters.

Concept / Approach:
Maternal uncle means the brother of the mother. So for D, whose mother is B sister, F must be a brother of that same sister. That places F in the same sibling group as B and B sister. Nephews of F are the sons of his brothers and sisters. From the information given, these sons are A, the son of B, and D, the son of B sister.

Step-by-Step Solution:
Step 1: From "B sister has a son D and a daughter E", we know that D is a male child and E is a female child of B sister.Step 2: F is the maternal uncle of D. The mother of D is B sister, so F must be a brother of D mother. Therefore, F is a brother of B sister.Step 3: Since B and B sister are siblings, and F is also described as brother of that sister, B, F and that sister form a sibling group in the same generation.Step 4: A is the son of B, so A is a male child of one of F siblings.Step 5: D is a son of B sister, who is another sibling of F.Step 6: By definition, a nephew of F is the son of F brother or sister. A is the son of B (F sibling) and D is the son of B sister (another F sibling). So both A and D are nephews of F.Step 7: Therefore F has exactly two nephews in this family, A and D.

Verification / Alternative check:
Draw the family briefly. Place three siblings in one row: B, F and S (the sister). From B draw a downward arrow to A, labelled son. From S draw downward arrows to D (son) and E (daughter). Now, nephews of F are the male children of B and S. That is exactly A and D. E is a niece, not a nephew, and there is no other sibling of F mentioned whose children might add to the count. So the total is 2.

Why Other Options Are Wrong:
A count of 0 or 1 would ignore either A or D as nephews, which contradicts the definitions. A count of 3 or 4 would require additional male children of F siblings, but the question gives only two such sons: A and D. The information is complete enough to fix the number at 2.

Common Pitfalls:
Candidates sometimes misinterpret "F is the maternal uncle of D" to mean that F is D father, which is incorrect; a maternal uncle is the mother brother, not the father. Another common mistake is to assume F is the same person as B without reading carefully. The appearance of a new letter usually indicates a new individual, and using that fact simplifies the counting.

Final Answer:
F has 2 nephews in this family.