Compare the estimated average rate of change for the graphed cubic function b\left(x\right)\ =\ \sqrt[3]{3x+9} to the estimated average rate of change of the square root function d\left(x\right)\ =\ \sqrt{-3x+9} over the interval [-12, -3]. Which comparison is true?
• The estimated average rate of change of b (x) is greater than the estimated average rate of change of d (x) because b (x) is increasing over the interval but d (x) is decreasing.
• The estimated average rate of change of d (x) is greater than the estimated average rate of change of b (x) because d (x) is positive over the interval but b (x) is negative.
• The estimated average rate of change of b (x) is greater than the estimated average rate of change of d (x), but both rates are positive.
• The estimated average rate of change of d (x) is greater than the estimated average rate of change of b (x), but both rates are negative.