g which of the following is true of the market demand for a public good? a. the efficient quantity of a public good produced occurs where the marginal utility from the last dollar spent on the good is zero. b. the market demand curve for a public good is the sum of the quantities demanded by each consumer at a given income level. c. the market demand curve for a public good is the vertical sum of individual consumers' demand curves. d. the efficient quantity of a public good produced occurs where the market demand curve intersects the market supply curve. e. the market demand curve for a public good is the horizontal sum of individual consumers' demand curves.