To determine the coordinates of vertex \( X' \) after reflecting triangle \( XYZ \) over a horizontal line, we need to know the original coordinates of vertex \( X \) and the line of reflection.
Let's denote the coordinates of vertex \( X \) as \( (x, y) \). When reflecting over a horizontal line, the x-coordinate remains the same, while the y-coordinate transforms based on the line of reflection.
If we know the y-coordinate of the line of reflection is \( k \), the reflection of point \( (x, y) \) is given by:
- \( X' = (x, 2k - y) \)
Without the specific coordinates of \( X \) or the line of reflection, we can only provide the response based on the context provided. Thus:
- If we assume \( X \) was at \( (x, y) \) and we don't know \( k \), it's impossible to solve for \( X' \) without knowing either the specific coordinates of \( X \) or the line of reflection.
Therefore, please provide the coordinates of vertex \( X \) and the line of reflection for a proper evaluation or check through given options based on the context of reflection.