The best measurement for comparing the standard of living between two countries is:

There are some special types of goods for which supply cannot change, irrespective of the length of time allowed for change, such as Beethoven symphonies. The price elasticity of supply for these goods is _____

a. infinite b. nonexistent c. negative d. zero e. unity

Cartels are difficult to maintain because

a. antitrust laws are difficult to enforce. b. cartel agreements are conducive to monopoly outcomes. c. there is always tension between cooperation and self-interest in a cartel. d. firms pay little attention to the decisions made by other firms.