please answer

1, The circular-flow diagram illustrates that, in markets for the factors of production, a, households are sellers, and firms are buyers, b, households are buyers, and firms are sellers. c. households and firms are both buyers. d. households and firms are both sellers. (1 ) 2. An economy produces ice-creams and lemonade, If a medical research finds that lemonade increases life expectancy, then consumers' preferences would change, it would a. expand the production possibilities frontier. b, contract the production possibilities frontier. c, move the economy along the production possibilities frontier. d. move the economy inside the production possibilities frontier. (1) 3, Adam Smith's "invisible hand" refers to a. the subtle and often hidden methods that businesses use to profit at consumers' expense. b, the ability of free markets to reach desirable outcomes, despite the self-interest of market participants. c, the ability of government regulation to benefit consumers, even if the consumers are unaware of the regulations. d. the way in which producers or consumers in unregulated markets impose costs on innocent bystanders. (1)