The inventory records for Radford Co. reflected the following Beginning inventory @ May 1 1700 units @ $ 5.00 First purchase @ May 7 1800 units @ $ 5.20 second purchase @ May 17 2000 units @ $ 5.30 Third purchase @ May 23 1600 units @ $ 5.40 Sales @ May 31 5400 units @ $ 6.90 Determine the amount of gross margin assuming the weighted average cost flow method. (Round your intermediate calculations to 2 decimal places.) Select one: A. $20,520 B. $8100 C. $9018 D. $29,160