a The diagram to the right illustrates a competitive market in which the product provides an external benefit. If a voucher equal to $20/unit (i.e., a voucher equal to the marginal external benefit) is given to consumers, then total surplus will A. fall by Area D. B. fall by Area A+B. C. fall by Area B. D. rise by Area C+D. E. rise by Area C + F. 65- 60 55 50- 45 S-MCp-MC 40 Marginal Benefit, Marginal Cost (S) C 35- 30 25 20 AB 15- 10 m 54 0-4 0 MBS D = MB 10 20 30 40 50 60 70 80 90 100 110 120 Quantity