Look at the graph. On a coordinate plane, a line with negative slope goes through points (0, 2) and (4, 0).

To find the rate of change of the function, Kevin did the following:

StartFraction 0 minus (negative 1) Over 2 minus 2.5 EndFraction = StartFraction 1 Over negative 0.5 EndFraction = negative 2.

What was Kevin’s mistake?
He incorrectly chose (–1, 2.5) as a point on the graph.
He incorrectly chose (0, 2) as a point on the graph.
He mixed up the numerator and the denominator of the fraction.
He subtracted –1 from 0 when he should have added –1 to 0.