How is price and quantity determined in a perfectly competitive market? How is economic profit calculated? In a perfectly competitive market in short-run equilibrium O A. market supply and market demand determine the price and quantity bought and sold in the market OB. the price and quantity bought and sold in the market are determined by the shutdown point OC. only supply determines the price and quantity bought and sold in the market because the good has many substitutes OD. only demand determines the price and quantity bought and sold in the market because all firms are price takers When a firm makes an economic profit in the short run, it is calculated as O A. marginal revenue minus marginal cost, multiplied by the quantity produced OB. market price minus marginal cost OC market price minus average total cost, multiplied by the quantity produced OD. marginal revenue minus average total cost