Carver Corporation produces a product that sells for $40. Variable manufacturing costs are $18 per unit, and fixed manufacturing costs are $5 per unit based on the current level of activity. A selling commission of 15% of the selling price is paid on each unit sold, and fixed selling and administrative costs are $4 per unit based on the current level of activity. The contribution margin per unit is

a. $7.

b. $17

c. $22.

d. $16.

e. Not determinable.