The following production and average cost data for two levels of monthly production volume have been supplied by a company that produces a single product: Production volume 3,000 units 4,000 units Direct materials $76.70 per unit $76.70 per unit Direct labor $39.70 per unit $39.70 per unit Manufacturing Overhead $94.80 per unit $76.30 per unit The best estimate of the total variable manufacturing cost per unit is: A. $76.70 B. $116.40 C. $20.80 D. $137.20