Answer:
B. Undefined.
Explanation:
We have been given a graph of a vertical line and we are asked to choose the correct option that describes the slope of our given line.
Since we know that slope represents the relation between rise and run of a function, where, rise is defined by the difference between two y-coordinates and run is defined by difference between x-coordinates of the same y-coordinates.


Since our vertical line passes through point (6,0) , so x coordinates will be 6 for any two y-coordinates.


Since any number divided by 0 is undefined, therefore, the slope of our given line is undefined and option B is the correct choice.