The question asks for the multiplicative rate of change which has a formula:
[ f(x2) / f(x1) ] / (x2 - x1)
4/8 / (-2 - (-3)) = 0.5
The other points can be tested to see if the multiplicative rate of change is equal for all values of x. By doing the same for the other points, the rate of change is found to be the same.
So, the answer is c. 0.5.