]:Using your own words, please make summary with no more than 250 words emphasizing the meaning of each KEY CONCEPTS Chapter 1: scarcity, economics, efficiency, equality, opportunity cost, rational people, marginal change, incentive, market economy, property rights, market failure, externality, market power, productivity, inflation, business cycle. Chapter 2: circular-flow diagram, production possibilities frontier, microeconomics, macroeconomics, positive statements, normative statements. Chapter 3: absolute advantage, opportunity cost, comparative advantage, imports, exports. Chapter 4: market, competitive market, quantity demanded, law of demand, demand schedule, demand curve, normal good, inferior good, substitutes, complements, quantity supplied, law of supply, supply schedule, supply curve, equilibrium, equilibrium price, equilibrium quantity, surplus, shortage, law of supply and demand