Paolucci Corporation's relevant range of activity is 9,000 units to 18,000 units. When it produces and sells 13,500 units, its average costs per unit are as follows:

	Average Cost per Unit
Direct materials	$	7.20
Direct labor	$	4.10
Variable manufacturing overhead	$	2.10
Fixed manufacturing overhead	$	3.90
Fixed selling expense	$	1.40
Fixed administrative expense	$	0.70
Sales commissions	$	1.35
Variable administrative expense	$	0.60

If 12,500 units are sold, the variable cost per unit sold is closest to:

a. $21.35

b. $13.40

c. $17.30

d. $15.35