Andi Company purchased merchandise inventory with an invoice price of $6,000 and credit terms of 1/15, n/30 (invoice dated December 1, 2020). $1,000 of the merchandise inventory was returned on December 7, 2020. What is the net cost of the goods if Andi Company pays within the discount period?

a. $4,950

b. $5,000

c. $5,880

d. $6,000