5. Refer to the graph 1. In which of these markets is an externality present? a. in Market A b. in Market B c. in both Market A and Market B d. Neither market exhibits an externality. 6. Refer to the graph 1. Which of the following statements is correct? a. Market A exhibits a negative externality because the marginal private benefit exceeds the marginal social benefit. b. Market B exhibits a negative externality because the marginal social cost exceeds the marginal private cost. c. Market A exhibits a negative externality because the marginal social benefit exceeds the marginal private benefit. d. Market B exhibits a positive externality because the marginal private cost exceeds the marginal social cost. 7. Refer to graph 1. In which of the markets is the quantity Q1 less than the economically efficient quantity? a. in Market A b. in Market B C. in both markets d. in neither of the two markets