Use the Following Information for Any or All of Questions

Use the following information for any or all of Questions .
Suppose the marginal benefits and marginal costs of tire production in the U.S. are modeled as follows, where Q is in millions:
MSB = 12 - 0.4Q MPB = 12 - 0.3Q MSC = MPC = 2 + 0.1Q
-The dollar value of a retail (or front-end) disposal charge needed to restore efficiency to this market would be

A) $4
B) $2
C) $6
D) $20