Melody has a credit card that uses the previous balance method. The opening balance of one of her 30-day billing cycles was $0, but this was her balance for only the first 15 days of the billing cycle. She then made a purchase that increased her balance to $4800, and her balance stayed this amount for the remainder of the billing cycle. If her credit card's APR is 29%, how much was Melody charged in interest for the billing cycle? A. $57.21 B. $0 C. $139.20 D. $114.41