A Federal Reserve publication notes "Airlines have high fixed costs." Source: Scott A. Wolla and Carolyn Backus, "The Economics of Flying: How Competitive Are the Friendly Skies?" Federal Reserve Bank of St Louis, Page One E Which of the following is likely to be one of the most important fixed costs for an airline? A. the cost of its planes O B. the cost of food and beverages O C. the cost of supplies, such as toilet paper O D. the wages and salaries it pays to its employees