Answer: A) x = -8
There is a hidden electric fence of sorts where the graph slowly approaches this vertical line but never touches or crosses it. It might help to draw in a dashed vertical line through -8 on the x axis.
A vertical asymptote occurs when a division by zero error happens. For instance, the equation y = 1/(x+8) has a division by zero error when x = -8 since x+8 = -8+8 = 0 is in the denominator.