Which of the Following Is a Correct Statement

Which of the following is a correct statement?

A) To obtain the economy's marginal benefit for a public good, marginal benefits of all individuals at each quantity have to be added.
B) To obtain the economy's marginal benefit for a public good, the quantity that all individuals are willing to buy at each price must be added.
C) To obtain the economy's marginal benefit curve for a public good, we sum the individual demand curves horizontally.
D) Because public goods are nonexcludable, the economy's marginal benefit curve for a public good is the same as its marginal cost curve.
E) None of the above answers is correct.