Answer: B) The slope is zero
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Step-by-step explanation:
Any horizontal line will always have a slope of 0. This is because there is no change in y (aka the rise is 0).
So we could say something like
slope = rise/run = 0/1 = 0
The run can be anything we want, and we'd still get 0 every time.
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Another way to see this is to pick two points from this line. Whichever points are selected, they are plugged into the slope formula
m = (y2-y1)/(x2-x1)
You'll find that the y2-y1 expression turns into 0. Why? Because y1 and y2 are the same, so they subtract to 0. It doesn't matter what x2-x1 turns into.