Quayle Bookstore had 500 units on hand at January 1, costing $9 each. Purchases and sales during the month of January were as follows: Date Purchases Sales Jan. 14 380 @ $15 Jan. 17 250 @ $10 Jan. 25 250 @ $12 Jan. 29 260 @ $17 Quayle maintains perpetual inventory records. According to a physical count, 360 units were on hand at January 31. The cost of goods sold at January 31, under the FIFO method is: O a. $5900 O b. $6000 c. $5800 d. $5500