Imagine a city plans to upgrade its recycling program. Which option best represents the Marginal Social Benefit (MSB) of this improvement, taking into account both individual and societal advantages?

The marginal social benefit of a recycling upgrade is the total gain that society enjoys from the program, which includes the benefit each person receives plus the extra benefit that spills over to the community. It adds the private benefit that citizens see—such as cheaper recycled goods or lower waste disposal costs—to the external benefit, like cleaner air, less landfill use, and lower future waste costs. Thus, the MSB is the sum of the private benefit and the external benefit. For example, if a city’s new recycling policy lets residents buy cheaper recycled products and also reduces landfill costs by $10 million, the MSB is the $10 million plus the savings to consumers. This combined figure tells planners whether the program is worth the investment.