If points T and T′ have the same x-coordinate after the reflection, that means they are positioned vertically with respect to one another. This indicates that the line of reflection must be horizontal, as reflecting a point vertically across a horizontal line does not change its x-coordinate.
Therefore, the correct answer is:
The line of reflection is horizontal.
Here's the reasoning:
- When a point is reflected over a horizontal line (like the x-axis), the y-coordinate changes (it becomes the opposite of the original), while the x-coordinate remains the same.
- Since T and T′ have the same x-coordinate, they must be symmetric with respect to a horizontal line of reflection.
So, T and T′ sharing the same x-coordinate confirms that the line of reflection is indeed horizontal.