If X is the brother of the son of Y’s son, How is X related to Y?

The correct answer is: Cousin.

X is the brother of the son of Y’s son. This means that X and Y have a common son, and X is the brother of that son. This makes X and Y cousins.

Here is a diagram to illustrate the relationship between X and Y:

[Diagram of a family tree with X and Y as cousins]

Y has a son, who is X’s brother. This makes X and Y cousins.

The other options are incorrect because they do not accurately reflect the relationship between X and Y.

• Option A is incorrect because X is not Y’s son.
• Option B is incorrect because X is not Y’s brother.
• Option D is incorrect because X is not Y’s grandson.
• Option E is incorrect because X is not Y’s uncle.