Because of resource scarcity, economies must make choices about the goods that can be produced with an efficient utilization of resources. The economy also has to decide how to produce the goods (techniques of production: capital-intensive or labor-intensive) and for whom to produce the goods (distribution of income and wages). The production-possibility frontier offers different combinations of two commodities that can be produced using the available resources and technology. The marginal rate of technical substitution, which is the rate at which part of a quantity of a good is sacrificed in order to produce an additional unit of the other good, keeping the total output constant, has to be established for the two goods. The prices and quantities are then set through demand and supply. At this point, the role of the government is essential to bring equilibrium to the market through supply-side policies (price floor and price ceiling). The economy has to develop so that it addresses the needs and wants of the present generation without trading off the ability of future generations to address their wants and needs.