31. At March 1, 2017, Hall Company had beginning inventory consisting of 200 units with a unit cost of $7. During March, the company purchased inventory as follows: March 10 March 20 400 units at $7/unit 600 units at $8/unit The company sold 1,000 units during the month for $12 per unit. Hall Company uses the average cost method. Heineken's gross profit for the month of March is a. $4,500 b. $7,500 c. $9,000 d. $12,000