Answer: Option (a) is the correct answer.
Explanation:
In a graph, the meaning of vertical line is line parallel to y-axis
Equation of y-axis is x = 0.
So, the equation of any line parallel to y-axis is given by x = a. Where a is any real number. As we have to find vertical line passing through (1, -1) so we do not need another point to determine the equation of vertical line. Thus, we can find the equation of vertical line by considering only a single point.
So, the equation of vertical line passing through point (1, -1) is x = 1.