Concept:Cost of goods sold is calculated using opening stock, purchases, and closing stock.Explanation:Cost of goods sold = Opening stock + Purchases − Closing stock.Substitute the given values: 10,000+100,000−20,000.First, 10,000+100,000=110,000.Then, 110,000−20,000=90,000.So, the cost of goods sold is Le90,000.Answer:C. Le 90,000