Polished is a personal styling company that employs staff to work in one of three service lines: Corporate Styling, Personal Styling, and Makeovers. It has recently decided to allocate the cost of its store rent to the service lines. Which of the following is the most appropriate cost driver? a. Average customer ratings for each service line b. The proportion of customers in each service line O c. The proportion of staff working in each service line O d. The number of staff in the accounting department O e. The proportion of floor space occupied by staff working in each service line