The production possibilities curve illustrates the basic principle that

• A. if all the resources of an economy are in use, more of one good can be produced only if less of another good is produced.
• B. the production of more of any one good will in time require smaller and smaller sacrifices of other goods.
• C. an economy will automatically obtain full employment of its resources.
• D. an economy's capacity to produce increases in proportion to its population size.