What type of curve illustrates the marginal cost of producing one more unit of a good or service?

The supply curve illustrates the marginal cost of producing one more unit of a good or service. This is because the supply curve reflects the relationship between quantity supplied and the price of a good or service. When producers are willing to supply more of a good, they must cover their marginal costs, which tend to increase as production expands. This relationship demonstrates that the price at which a good is supplied is closely tied to the costs of producing it.

As the quantity produced increases, if the marginal costs rise—often due to factors such as resource limitations or increased labor costs—this will be reflected in an upward slope of the supply curve. Therefore, the supply curve can be seen as illustrating the marginal cost of production, as it effectively indicates how much producers are prepared to produce at different price levels, given their costs.

The other options do not represent marginal cost. The demand curve shows consumer willingness to pay at various prices, the marginal revenue curve illustrates the additional revenue gained from selling one more unit, and the equilibrium price curve finds the price where supply meets demand. None of these directly represent the increase in production costs for additional units as effectively as the supply curve does.