Your Firm Purchases Goods from Its Supplier with a Discount

Your firm purchases goods from its supplier with a discount of 1%,and a discount period of 15 days.If the effective annual cost of forgoing the discount is 15.8%,what is the length of the credit period?

A) 10 days
B) 20 days
C) 30 days
D) 40 days
E) 50 days