Beginning inventory $18000, purchases $70000, purchase returns $3000, freight $6000, ending inventory $12000? Select one: a. Using a periodic inventory system, the cost of goods sold was $85000. b. Using a periodic inventory system, the cost of goods sold was $79000. OC. Using a periodic inventory system, the cost of goods sold was $88000. d. Using a periodic inventory system, the cost of goods sold was $91000