The Demand Curve for Public Goods Is

The demand curve for public goods is

A) found by horizontally summing each voter's desired quantity of the public good at various reservation prices.
B) found by surveying voters on how much of a particular public good they want at various reservation prices.
C) found by vertically summing each voter's reservation price for a given level of public good.
D) unknown,because of the nonrival and nonexcludable nature of the good.
E) found by withdrawing the public good and measuring the public outcry.