If A is the mother of B and K, D is the husband of A, and E is the son of D's brother, what is the relation of A with E?

Introduction / Context:
This blood relation question mixes parent–child relations with sibling and in-law connections. You are given that A is the mother of B and K, that D is A's husband, and that E is the son of D's brother. The goal is to determine how A is related to E. This is a common structure where you must identify that the child of a husband's brother is a nephew, and the husband's wife becomes the aunt.

Given Data / Assumptions:
- A is the mother of B and K. - D is the husband of A. - Therefore, D is the father of B and K. - D has a brother, and E is that brother's son. - All relations are by blood or marriage in a standard nuclear family context.

Concept / Approach:
First, recognise that D's brother is the paternal uncle of A's children B and K. E is the son of that uncle, making him a cousin of B and K. From A's perspective, E is the son of her brother-in-law (her husband's brother). The standard family term for the relation between a woman and the children of her siblings or her husband's siblings is aunt. Therefore, A is E's aunt, more specifically his paternal aunt by marriage.

Step-by-Step Solution:
Step 1: Note that A and D are married, with children B and K. So A is the mother and D is the father of B and K. Step 2: D has a brother. Let us call this brother X. X and D share the same parents. Step 3: E is the son of D's brother X. Thus E is a child of A's brother-in-law. Step 4: For B and K, X is their paternal uncle, and E, as X's son, is their first cousin. Step 5: From A's viewpoint, E is the child of her husband's brother, that is, the child of her brother-in-law. Step 6: The usual term for the relation between a woman and the child of her sibling or her husband's sibling is aunt. Hence, A is E's aunt.

Verification / Alternative check:
Draw a family tree with D and his brother X on one level. D is married to A, and they have children B and K. X has a child E. From E's position, his father's brother is D, and D's wife is A. The wife of one's paternal uncle is also called aunt. So both via blood and via marriage, E sees A as an aunt figure. This aligns with the standard use of the term aunt in family relationship puzzles.

Why Other Options Are Wrong:
- Mother in law: A would be E's mother-in-law only if E were married to A's daughter. No such information is provided. - Sister in law: A is married to D, and D's brother's wife would be A's sister-in-law, not A herself. - Sister: For A to be E's sister, they would need to share parents, which they do not. - Cousin: Cousin is a relation between people of the same generation, not between a person and the parent's generation.

Common Pitfalls:
A frequent mistake is to focus solely on E as the cousin of B and K and then incorrectly transfer that cousin label to describe A's relation to E. Remember that relationships depend on generation differences as well as shared ancestors. Another pitfall is confusing sister-in-law with aunt; sister-in-law describes relations between adults of the same generation, whereas aunt describes the relation between that generation and the next generation.

Final Answer:
A is related to E as his aunt.