If A is the brother of the son of B's son, then how is A related to B?

Introduction / Context:
This blood relation problem focuses on understanding multi step phrases like the son of B's son. These phrases frequently appear in exams and usually describe grandchildren, great grandchildren or similar relations. The goal is to decode the expression and then attach the correct relationship term to A relative to B.

Given Data / Assumptions:

• B has a son; call this person X.
• The son of B's son means the son of X, which is a grandchild of B.
• A is the brother of that son, so A is also a child of X.
• We assume a standard family structure with no adoptions or step relations.

Concept / Approach:
The expression the son of B's son already points to a grandchild of B. Since A is the brother of that person, A is another child of B's son. That places A in the same generation as that grandchild, directly under B's son. Whenever a person is a child of the child of B, that person is a grandchild of B. Thus A is a grandson of B (and male because he is called a brother), regardless of exact names.

Step-by-Step Solution:
Step 1: Let B's son be X. Then X is one generation below B.Step 2: The son of X is one generation below X, which is two generations below B. This person is a grandchild of B.Step 3: A is described as the brother of that son. That means A is also a child of X.Step 4: Therefore A is a child of B's son and hence a grandchild of B.Step 5: Since A is called a brother, A is male, so the precise term is grandson.

Verification / Alternative check:
Imagine a simple family tree. B at the top, B's son X below, and two children of X at the bottom: one child Y and his brother A. The relation between A and B runs through X. That is A to X (one step) and X to B (another step). Two steps up from A leads to B, which is the standard grandparent relation. This confirms that A is a grandchild of B, and given that A is male, he is a grandson.

Why Other Options Are Wrong:
Brother is wrong because A is not in the same generation as B, but two generations below.Son is wrong because that would require A to be a direct child of B, not a child of B's son.Father is completely opposite to the direction of the given relations.Uncle would require A to be a sibling of one of B's children, not a child of B's grandchild.

Common Pitfalls:
The most common error is to move only one generation at a time and stop too soon. Students sometimes think the son of B's son is simply B's son again, which is incorrect. Another error is forgetting that brother only tells us gender and sibling relation, not generation. Always count how many parent steps you move between the two target people to correctly identify grandparent or grandson level relations.

Final Answer:
A is related to B as B's Grandson.