Displayed in the diagram below are conditions in the market for residential Internet access in a U.S. state. The government of this state has determined that access to the Internet improves the learning skills of children, which it has concluded is an external benefit of Internet access. The government has also concluded that if these external benefits were to be taken into account, 3 million residences would have Internet access. Suppose that the state government’s judgments about the benefits of Internet access are correct and that it wishes to offer a per-unit subsidy just sufficient to increase total Internet access to 3 million residences. What per-unit subsidy should it offer? Use the diagram to explain how providing this subsidy would affect conditions in the state’s market for residential Internet access.