Final answer:
Economic profit is the best measure of a firm's performance because it takes into account both explicit and implicit costs.
Step-by-step explanation:
Economic profit is the best measure of a firm's performance because it takes into account both explicit and implicit costs. While accounting profit only considers explicit costs, economic profit includes the opportunity cost of using all resources. By subtracting both explicit and implicit costs from total revenue, economic profit provides a more comprehensive assessment of a firm's profitability.