ABC produces a product that sells for $20. Variable manufacturing costs are $8 per unit. Fixed manufacturing costs are $3 per unit based on the current level of activity, and fixed selling and administrative costs are $4 per unit. A selling commission of 10% of the selling price is paid on each unit sold. What is the contribution margin per unit? Select one: O a. $6 O b. $3 O C. $12 O d. $10