The inventory records for Radford Co. reflected the following: Beginning inventory @ May 1 700 units @ $3.00 First purchase @ May 7 800 units @ $3.20 Second purchase @ May 17 1000 units @ $3.30 Third purchase @ May 23 600 units @ $3.40 Sales @ May 31 2400 units @ $4.90 If the company uses the weighted average inventory cost flow method, what is the average cost per unit (rounded) for May? 200 Select one: O a. $3.29 O b. $3.23 c. $3.18 d. $4.90