The slope (m) of a graph can be calculated using the formula:
[tex]\begin{gathered} m=\text{ }\frac{\Delta\text{ y}}{\Delta x} \\ =\frac{y_2-y_1}{x_2-x_1} \end{gathered}[/tex]
An undefined slope occurs when:
[tex]\Delta x\text{ = 0}[/tex]
This implies that the x-coordinates never change no matter what the y-coordinate is.
Hence, the graph of the line slope of undefined is Option C
