Variable costs per unit: Direct material $5.00 Direct labor 4.00 Manufacturing overhead 6.00 Selling and administrative costs 3.00 Total cost per unit $18.00 Annual fixed operating costs: Manufacturing overhead $6,200,000 Selling and administrative costs 3,700,000 Total annual fixed cost $9.900.000 Note: All monetary amounts are in US dollars. The dollar sales volume required in the coming year to earn the same after-tax net income as the past year is a) C US $20,160,000. b) C US $21,600,000. c) C US $23,400,000. d) C US $26,400,000