Final answer:
The correct answer should represent a vertical line parallel to the y-axis, which none of the provided options does. Typically, the equation x = a (where a is a constant) describes such a line. Therefore, it seems the question may have an error or the right option is missing.
Step-by-step explanation:
The question asks which equation represents a line that is parallel to the y-axis. A line parallel to the y-axis has an undefined slope and takes the form of x = a, where a is any real number, since it is a vertical line. However, this is not reflected in the given options. Among the given choices:
- Option A: y = -7 represents a horizontal line at the value -7 on the y-axis.
- Option B: r = -6 does not represent an equation in the x-y plane.
- Option C: y = x + 1 represents a line with a positive slope of 1.
- Option D: y = 1 represents a horizontal line at the value 1 on the y-axis.
Since none of the options precisely describe a vertical line parallel to the y-axis, we might consider the question to be incorrect or lacking the right option. Typically, an equation like
x = 5
would represent such a line.