In fiscal year 2021, Walmart Inc. (WMT) reported annual revenue of $572.75 billion, gross profit of $143.75 billion, and net income of $13.67 billion. Costco Wholesale Corporation (COST) had revenue of $195.9 billion, gross profit of $25.25 billion, and net income of $5.01 billion. a. Compare the gross margins for Walmart and Costco. b. Compare the net profit margins for Walmart and Costco. c. Which firm was more profitable in 2021