A firm offers credit terms of 3/15, net 20 to its customers, which means the firm allows its customers to:

a. take a 20 percent discount on the invoice price if payment is made on or before Day 3 of the billing cycle; otherwise, the entire bill is due by Day 15.

b. take a 15 percent discount on the invoice price if payment is made on or before Day 20 of the billing cycle; after that, only a 3 percent discount will be available.

c. take a 3 percent discount on the invoice price if payment is made on or before Day 15 of the billing cycle; otherwise, the entire bill is due by Day 20.

d. take a 15 percent discount on the invoice price if payment is made on or before Day 3 of the billing cycle; otherwise, the entire bill is due by Day 20.

e. take a 20 percent discount on the invoice price if payment is made on or before Day 15 of the billing cycle; after that, only a 3 percent discount will be available.