Pedregon Corporation has provided the following information:

Cost per Unit Cost per Period

Direct materials $ 6.40

Direct labor $ 3.20

Variable manufacturing overhead $ 1.20

Fixed manufacturing overhead $ 14,400

Sales commissions $ 0.40

Variable administrative expense $ 0.45

Fixed selling and administrative expense $ 3,300

If the selling price is $20.20 per unit, the contribution margin per unit sold is closest to:

A) $5.35 B) $6.20 C) $8.55 D) $10.60

Please explain correct answer.