Answer:
A. XY
Explanation:
The answer is XY because it is the same length as XZ. I didn't determine this by guessing, but by eliminating the wrong answer choices. The tick marks indicate what lines are congruent to each other. The answer can't be C because AY is congruent to YC since they both have 3 tick marks, indicating that they are congruent to each other. Same goes for the others.