If variable manufacturing costs are $9 per unit and total fixed manufacturing costs are $371,000, what is the manufacturing cost per unit if a. 5,300 units are manufactured and the company uses the variable costing concept? $ b. 7,000 units are manufactured and the company uses the variable costing concept? $ c. 5,300 units are manufactured and the company uses the absorption costing concept? $ d. 7,000 units are manufactured and the company used the absorption costing concept? $