Final answer:
The equation that represents a vertical line on the graph is x + 4 = 0 (option B).
Step-by-step explanation:
The equation that represents a vertical line on the graph is x + 4 = 0 (option B).
When a line is vertical, it is parallel to the y-axis, and its equation will be in the form x = k, where k is a constant. In this case, the line is parallel to the y-axis and passes through the point (-4, 0). Therefore, the equation is x + 4 = 0.