In the context of a new public transportation system, which scenario best demonstrates the relationship between Marginal Social Cost (MSC) and Marginal Social Benefit (MSB) while highlighting the overall social benefit to the community?

A new bus line is added to a city, and each extra rider costs the city a little more in fuel, wear on roads, and noise, which is the marginal social cost (MSC). At the same time, every rider reduces traffic congestion and pollution, giving a marginal social benefit (MSB) to everyone else. When planners choose a level of service where MSC equals MSB, the community gets the greatest overall benefit, because the cost of adding another bus is exactly offset by the benefit to all. For example, if the cost of an extra bus is $30 per day and the benefit to commuters and the environment is also $30, then the system is socially optimal. This balance shows how the social benefit is maximized when the marginal costs and benefits are equal.