Which of the following does the author offer as evidence to support the point that, for a time, serialization was highly successful?

Choice A is the best answer. The author asserts that The Pickwick Papers “truly popularized” the form of the serialized novel, noting that the first installment had a print order of 1,000 copies and that circulation had climbed to 40,000 “by the time the final entry was published.” Choice B is incorrect because the passage indicates that unresolved plots and elliptical section breaks were merely features of serialized novels, ones that helped promote serialization’s success but were not themselves evidence of the success of serialization. Choices C and D are incorrect because the passage cites the decrease in cost of book production and the development of new mediums, such as radio, as causes of the decline of serialization (“slowly shriveled away”).