Answer:
<em>Answer: C. Zero</em>
Step-by-step explanation:
<u>The Slope of a Line</u>
Suppose we know a line passes through points A(x1,y1) and B(x2,y2). The slope can be calculated with the equation:

The line shown in the image is horizontal, i.e. all of its points have the same y-coordinate regardless of their x-coordinate.
Take two random points on the line like (0,-2) and (2,-2), the slope is:

The slope is zero
Answer: C. Zero