Patterson's Department Store prepares monthly income statements by sales departments. These income statements are organized to show contribution margin, performance margin, and responsibility margin for each sales department, as well as operating income for the store as a whole.

All of the following costs are traceable to specific sales departments except:

a.Cost of goods sold.

b. Depreciation of equipment and fixtures used in the department.

c. Advertising a special sale in a particular department.

d. The salary of the store manager.