Use the Figure Below to Answer the Following Questions

Multiple Choice

Use the figure below to answer the following questions.
Figure 17.2.1
-Refer to Figure 17.2.1.Curve MB_A is Andrew's marginal benefit curve for a private good and curve MB_B is Betty's marginal benefit curve for the same private good.If Andrew and Betty are the only two consumers in the economy,which point would be on the economy's marginal social benefit curve?

A) price of $20,quantity of 3 units
B) price of $20,quantity of 4 units
C) price of $10,quantity of 4 units
D) price of $30,quantity of 0 units
E) price of $60,quantity of 1 units