Use the following to answer the question below. Suppose the marginal benefits and marginal costs of tire production in the U.S. are modeled as follows, where Q is in millions: MSB = 12 -0.4Q MPB = 12 -0.3Q MSC = MPC = 2 + 0.1Q 4. In the absence of environmental policy, the number of tires produced in a competitive market is A. 20 million B. 25 million C. 4 million D. none of the above 5. Available data on the generation of MSW in the United States indicates that A. durable goods represent the largest proportion by weight of all product groups B. plastics are the largest proportion by weight across all materials groups C. containers and packaging are the largest proportion by weight of all product groups D. none of the above 6. In the United States, the recovery rate for plastic wastes A. has been declining as the use of plastics has been decreasing over time B. has been rising because of low-cost methods for sorting by resin content C. is waning because of the absence of lucrative markets for all recycled plastics D. is generally low because of costly steps in the plastic recycling process 7. In the United States, the recovery rate for plastic wastes A. has been declining as the use of plastics has been decreasing over time B. has been rising because of low-cost methods for sorting by resin content C. is waning because of the absence of lucrative markets for all recycled plastics D. is generally low because of costly steps in the plastic recycling process