Sloan Sporting Goods has stores in four geographic regions. Each region has at least 20 stores. In the company's responsibility accounting system, sales are recorded separately for each sales department within each store. The total sales for a particular region are determined by: a. Using a separate revenue account to record the sales transaction for each region. b. Combining the total sales of all stores in that region. c. Taking a percentage of the company's total sales that is equal to the percentage of the company's stores located in that region . d. Adding together the sales tickets for all sales transactions in the region