Final answer:
The slope of a horizontal line is 0 because there's no vertical change as the x-value increases, while the slope of a vertical line is undefined due to a zero horizontal change. A diagonal line's slope depends on its direction and steepness, with a positive slope indicating an upward trend and a negative slope indicating a downward trend.
Step-by-step explanation:
To determine the slope of the dotted lines and reflection line, we need to refer to the definitions and characteristics of lines and their slopes. The slope is a measure of how steep a line is and is calculated as the rise over the run, which is the change in the y-values divided by the change in the x-values of two points on the line.
A horizontal line has a slope of 0 because there is no rise, the y-value does not change as the x-value increases. A vertical line has an undefined slope because the run is 0, so you would be dividing by zero, which is not possible. When a line has a positive slope, you can see the line move upwards as you move from left to right, meaning as the x-value increases, so does the y-value. In contrast, a line with a negative slope moves downwards as you move from left to right.
Given the options, if the dotted lines are horizontal, they would have a slope of 0 (Option A). If the dotted lines are vertical, they would have an undefined slope (Option B). If the reflection line is diagonal with an equal angle relative to the x-axis and y-axis, it would be reasonable to assume a slope of 1 or -1 (Options C and D). Without a graph to examine, we would match each description with the known properties of lines: horizontal lines have a slope of 0, vertical lines have an undefined slope, and diagonal lines have slopes that can be determined by their steepness and direction.