Why is the market demand curve for public goods calculated as a vertical summation of individual demand​ curves? A. because public goods require vertical summation to account for the higher level of fairness compared to private goods.
B. because public goods are finite in availability of​ consumption, so the vertical summation accounts for the limit.
C. because the public good is​ non-rival, so you and others can consume every unit of the good at the same time.
D. because public goods are the opposite of private​ goods, therefore the summing must be done similar to club goods.