Question

-4
0
1
undefined
Those are the answer options

Answer 1

The other answer is wrong...

Only horizontal lines produce a slope of 0.

On the other hand, vertical lines returns a slope of infinity, hence it will be undefined.

This is a common misconception, don’t be mistaken

Answer 2

The answer is 0 since the line is going straight up, there is no rise over run therefore, there is no slope.