Scenario: the Following Excerpt Is from "Throwing the Book at Apple

Scenario: The following excerpt is from "Throwing the Book at Apple" (Wall Street Journal, Review and Outlook, June 12, 2013) :
At the time, prior to the existence of the tablet device market that Jobs created with the iPad, Apple did not sell e-books. Amazon sold nine of every 10. Justice claims Jobs then forced Amazon and every other e-book distributor to adopt a new e-book pricing model that harmed consumers.
Yet the average retail price for "trade" e-books has since dropped to $7.34 from $7.97, and Amazon's Kindle is still the industry leader with Apple trailing in third. Over the same period readers bought 447% more e-books, and they can choose from dozens of tablets for titles and other media content.
-Refer to the scenario above.What market structure best describes the e-book market?

A) A monopoly
B) A competitive market with a few dominant firms producing substitutes
C) A competitive market with a few dominant firms producing identical goods
D) A perfectly competitive market