Final answer:
The equation that represents a line parallel to the x-axis is D. y = 5, because it describes a horizontal line with a slope of 0 at 5 units above the x-axis.
Step-by-step explanation:
The question is asking which equation represents a line parallel to the x-axis. A line parallel to the x-axis will have a slope of 0, meaning that it does not rise or fall regardless of how much it moves along the x-axis. From the given options, the equation that best fits this description is D. y = 5.
Let's explain further. The general form of a linear equation is y = mx + b, where m is the slope and b is the y-intercept. A slope of 0 yields a horizontal line, which means that for every point on that line, y will always have the same value. Therefore, an equation like y = 5 indicates a horizontal line 5 units above the x-axis, meaning it's parallel to the x-axis and has a slope of 0.