A and B are a married couple. X and Y are brothers, and X is the brother of A. How is Y related to B?

Introduction / Context:
In-law relationships are created through marriage. If A and B are married and X is A’s brother, then X is B’s brother-in-law. If Y is also X’s brother (i.e., Y is another brother of A), then Y likewise becomes B’s brother-in-law. The puzzle checks your ability to propagate the in-law link across siblings.

Given Data / Assumptions:

• A and B are married.
• X and Y are brothers.
• X is the brother of A → Y is also a brother of A (since X and Y are siblings).
• Standard definitions: sibling of your spouse is your brother-/sister-in-law.

Concept / Approach:
From marriage A–B, any sibling of A becomes an in-law to B. Since both X and Y are brothers of A, each is B’s brother-in-law. We do not need the genders of A and B explicitly; the “brother-in-law” label refers to the brothers of one’s spouse.

Step-by-Step Solution:

Verification / Alternative check:
No alternative fit is needed, because the role “brother-in-law” captures the relation of a spouse’s brother precisely. Options like “cousin” or “uncle” would require additional generational or parental details not present here.

Why Other Options Are Wrong:

• brother: That would require Y to share parents with B, not stated.
• cousin: Lateral relation, not formed by the A–B marriage.
• uncle: Would require Y to be the sibling of one of B’s parents.
• None of these: Not needed; “Brother-in-law” fits exactly.

Common Pitfalls:

• Forgetting that multiple siblings on one side of a marriage all become in-laws to the spouse.
• Assuming genders of A or B change the in-law label; they do not in this context.

Final Answer:

Brother-in-law