For a Public Good,which Statement(s)accurately Describe(s)the Marginal Social Benefit (MSB)

Multiple Choice

For a public good,which statement(s) accurately describe(s) the marginal social benefit (MSB) ? I.MSB equals the sum of the individual marginal benefits for all of the consumers of that unit.
II.MSB equals the sum of each consumer's willingness to pay for that unit.
III.MSB is greater than any individual marginal benefit.

A) I only
B) II only
C) I and II only
D) I,II,and III