Answer:
y = 5
Step-by-step explanation:
The y-axis and any lines that are parallel to it are vertical. Therefore, a line that would be perpendicular to the y-axis would need to be horizontal. All horizontal lines have a slope equal to 0 and are represented by the equation y = a constant, or a single number with no variables.
The only option that follows that format is y = 5, thus that is the answer.
