Answer:
Don't know why y'all are giving the other guy 1 star because he didn't even give the formulas. I'm taking the test anyways and the answer is C.
Step-by-step explanation:
the average rate of change of f(x) over the interval [8,12]
The formula for average rate of change of f(x) over the interval [a,b] is

Given interval is [8,12]
a= 8 and b = 12
So the average rate of change over the interval [8,12] is

So Option C