The three options that properly describe "slope" are:
A. run/rise
B. change in y-value over change in x-value
C. y↓(2) - y↓(1) / x↓(2) - x↓(1)
Additionally, "rise/run" (option D) is also correct, as it is just a rearrangement of options A and B. However, option E is incorrect because it describes the inverse of the slope.