Greetings.
A line goes through (-1,0) and (-1,1).
~ Theory ~
If both x-term for both ordered pairs have same value. The slope for line graph is undefined.
~ Proof ~
Using Rise/Run
![m = (1 - 0)/( - 1 - ( - 1)) \\ m = (1)/( - 1 + 1) \\ m = (1)/(0)](https://img.qammunity.org/2021/formulas/mathematics/high-school/uki6x7s2ylx0nzzd8s84dg27z32dluhx5f.png)
Because the denominator is 0, therefore, the slope is undefined.
Because from rise/run. We put the x-term to subtract another x-term. And if both x-terms have same value. It will give the run/denominator = 0.
Therefore the answer is a. Undefined