The correct answer is C. Total Cost.
Prime cost is the sum of direct labor costs and direct material costs. Variable overheads are costs that vary in direct proportion to the volume of production. Total cost is the sum of prime cost and variable overheads.
Cost of sales is the cost of the goods that a company has sold during a period. It is calculated by adding the cost of goods manufactured to the beginning inventory of finished goods and then subtracting the ending inventory of finished goods.
Production cost is the cost of producing a product. It is calculated by adding the cost of materials, labor, and overhead to the cost of goods manufactured.
Marginal cost is the change in total cost that results from a one-unit change in output. It is calculated by dividing the change in total cost by the change in output.