The following data pertain to Epsom Corporation's operations:

Unit sales	13,700 units
Selling price	$35 per unit
Contribution margin ratio	20%
Margin of safety percentage	10%

The variable expense per unit is: (Do not round intermediate calculations.)

a. $10.50 per unit

b. $3.50 per unit

c. $28.00 per unit

d. $7.00 per unit