Which one of the following could result from using an estimated level of activity as the cost driver? Question 9 options: a) Estimates are not completed until after the period is over, so gathering all the information would take a long time. b) Periodic demand and supply changes are not taken into account, so cost estimates could be less accurate. c) It can lead to the idea that as demand decreases, costs go up. d) Managers are constantly reminded that there is idle capacity