The equation that represents a line which is perpendicular to the x-axis is: x = 4
How to find the equation of the Line?
The general formula for the equation of a Line in slope intercept form is:
y = mx + c
where:
m is slope
c is y-intercept
A line that is perpendicular to the x-axis will have the equation starting with x before the equal to sign.
The only option showing that condition is x = 4