In 2007 Amazon. com began to sell its own Kindle e-readers, which helped energize the e-book market. In 2011 the company introduced a related low-cost tablet computer, the Kindle Fire, and by 2012, the Kindle Fire was estimated to constitute 50 percent of the tablets sold that used Google's Android mobile operating system. After its first full year of selling books in 1996, book publishers praised the new service as a great way to help them clear their backlists of slow-selling books. However, with the introduction of the Kindle, tensions began to build between publishers and Amazon. com. The company wanted to sell new e-books for a fixed price, well below what new printed books sold for, prompting many complaints from the publishing industry.

By 2010 the rift between book publishers and Amazon. com over the price of e-books had grown. The publishing company Macmillan Books threatened to pull its e-books from Amazon. com, which retaliated by removing all Macmillan books, both printed and electronic, from the site. However, within weeks, Amazon. com capitulated and allowed Macmillan and other publishers to set prices of e-books.

In 2009 the company introduced its first publishing line, AmazonEncore, dedicated to popular self-published and out-of-print books. It also let individuals publish their own e-books. In 2011 its e-book ambitions led to the launch of Amazon Publishing with the intent to develop and publish its own titles. That year Amazon. com announced that Kindle e-books were outselling all printed books. While many book publishers continue to derive significant revenue through sales at Amazon. com, the company is no longer considered by publishers merely as another bookseller. It is now also a major competitor in their industry.
Mark Hall © 1994–2013 Encyclopedia Britannica, Inc.

How does the author reveal a complicated connection between Amazon. com and traditional booksellers?

A. After its first full year of selling books in 1996, book publishers praised the new service as a great way to help them clear their backlists of slow-selling books.
B. In 2009 the company introduced its first publishing line, AmazonEncore, dedicated to popular self-published and out-of-print books.
C. In 2011 its e-book ambitions led to the launch of Amazon Publishing with the intent to develop and publish its own titles.
D. While many book publishers continue to derive significant revenue through sales at Amazon. com, the company is no longer considered by publishers merely as another bookseller.