The following cost items relate to the Brock Company. Classify each cost as a variable cost, a fixed cost, or a mixed cost by placing an X in the appropriate column. Each cost should be evaluated in terms of the volume of units of finished products produced. Also indicate with an X for each item if it is a product cost or a period cost. Variable, fixed, or mixed cost? Product or period cost? Cost Variable Fixed Mixed Product Period Executive salary Direct labor Direct materials Depreciation of Manufacturing equipment Indirect labor Factory utilities Delivery expense Television advertising Indirect materials