Answer:
B) Undefined
Step-by-step explanation:
Vertical lines do not have a horizontal change; the line goes straight up and down. In other words, the change in the x values between any points on the graph is always 0, which would make the denominator of the slope 0. Since anything divided by 0 is undefined, the slope of a vertical line is undefined.
Source: https://www.brightstorm.com/math/algebra/linear-equations-and-their-graphs/finding-the-slope-of-a-line-from-a-graph-problem-3/
