If X is the daughter of Y and Y is the brother of Z, how is X related to Z?

The correct option is Niece.

To determine the relation between X and Z, let us break down the given statements step-by-step:

1. Statement 1: "X is the daughter of Y"
This means Y is the parent (father or mother) of X, making X a female descendant (daughter) of Y.

2. Statement 2: "Y is the brother of Z"
This means Y and Z are siblings, specifically Y is a male sibling (brother) of Z.

3. Combining the relationships:
Since Y is the brother of Z, and X is the daughter of Y, X is the daughter of Z's brother.

The daughter of one's brother (or sister) is called a niece.

Therefore, X is the niece of Z.