Final answer:
The correct expression to calculate the average rate of change of k on -3 ≤ x ≤ 5 is option D. 5x + 55.
Step-by-step explanation:
The average rate of change of k on -3 ≤ x ≤ 5 can be found by taking the difference in the values of k at the endpoints of the interval and dividing it by the difference in the values of x at those endpoints. The correct expression to calculate the average rate of change of k on -3 ≤ x ≤ 5 is given by option D. 5x + 55.