B is the best answer.

In the first paragraph, the author contrasts two incidents that are said to exemplify the transformation in social values that forms the subject ofZelizer’s book. The second and third paragraphs consist of a brief history of that transformation, as Zelizer presents it, and an account of the factors she considers important in bringing it about. In the last paragraph, the author explains how Zelizer’s thesis differs from that of sociological economists. Thus, the passage serves primarily to present the central thesis of Zelizer’s book. A misrepresent the subject matter of the passage. D misrepresents the author’s approach. C is incorrect because although the passage does contrast two approaches, this contrast takes place only in the final paragraph.