The graph plots price versus quantity.The horizontal axis is labeled quantity. The vertical axis is labeled price. The graph shows a rising line labeled S and a falling line labeled D. The rising line labeled S starts from a point on the vertical axis and ends at a point on the top right. The falling line labeled D starts from a point on the vertical axis, goes down and to the right, passes through S and ends at a point on the bottom right. The line labeled S is shifted to the left. The shifted line labeled S 1 is parallel and to the left of line S. Refer to the diagram, in which S is the market supply curve and S1 is a supply curve comprising all costs of production, including external costs. Assume that the number of people affected by these external costs is large. If the government wishes to establish an optimal allocation of resources in this market, it should Multiple Choice tax producers so that the market supply curve shifts leftward. subsidize consumers so that the market demand curve shifts leftward. subsidize producers so that the market supply curve shifts leftward