Fast Track Auto produces and sells an auto part for $80 per unit. In 2020, 110,000 parts were produced and 75,000 units were sold. Other information for the year includes: Direct materials $23 per unit Direct manufacturing labor $5 per unit Variable manufacturing costs $1 per unit Sales commissions $8 per part Fixed manufacturing costs $770,000 per year Administrative expenses, all fixed $310,000 per year What is the inventoriable cost per unit using variable costing? A. $37 B. $29 C. $23 D. $28