When there are many producers and many consumers in an economy, the best way to achieve an efficient allocation of resources is to have a A. single planner who makes all production decisions and allocates all goods and services to consumers. B. freely operating economy with some very large firms that make most production and pricing decisions. C. freely operating economy in which all markets are perfectly competitive. D. centralized system in which the government owns all productive resources and allocates all goods and services to consumers.