The Construction of the Economy's Marginal Social Benefit Curve for a Public

The construction of the economy's marginal social benefit curve for a public good reflects the fact that

A) all the individuals can consume the same unit of the good.
B) the government can supply a public good at a lower cost than can a private supplier.
C) more than one supplier can provide the good.
D) the same unit of the good cannot be simultaneously shared by more than one person at a time.
E) demand for a public good is perfectly elastic.