Answer:
D
Explanation:
First, plot the points they gave you onto a graph (shown in the attached image). The slope is the rise (units up or down from a given point) over the run (units left or right from a given point).
So the slope is 6/4 because to get from the red point to the blue point, you rise 6, and run 4. And from blue to red you rise (remember rise goes up or down) 6 and run 4. 6/4 can be simplified to 3/2 so D is your answer :)