Last year, Gibson Inc. incurred the following costs:

Direct materials $50,000

Direct labor $20,000

Variable manufacturing overhead $60,000

Fixed manufacturing overhead $70,000

Variable selling expense $10,000

Fixed selling expense $30,000

Fixed administrative expense $36,000

Gibson produced and sold 10,000 units at a price of $31 each.

What is the conversion cost per unit?

a) $5.00

b) $15.00

c) $27.60

d) $20.00

e) $7.00