Advertising Costs The following graph (see Exercise 46) shows the weekly c...

Advertising Costs The following graph (see Exercise 46) shows the weekly cost of OHaganBooks.com’s online ad campaign for the six-week period since the start of July (t is time in weeks).

Use the graph to answer the following questions:

a. What was the average rate of change of cost over the entire six-week period?

b. What was the average rate of change of cost over the period [2, 6]?

c. Which of the following is correct? Over the period [2, 6],

(A) The rate of change of cost increased and the cost increased.

(B) The rate of change of cost decreased and the cost increased.

(C) The rate of change of cost increased and the cost decreased.

(D) The rate of change of cost decreased and the cost decreased.