21. Given the following data, calculate cost of goods sold using the FIFO costing method. Date Item Unit 33 units at $8 per 1/1 Beginning inventory unit Purchase of 12 units at $10 per 2/25 inventory unit Purchase of 25 units at $14 per 5/20 inventory unit Purchase of 5 units at $12 per 8/15 inventory unit Purchase of 12 units at $18 per 10/17 inventory unit 12/31 Ending inventory 18 units a. $720 b. $888 c. $1004 d. $1354