Although the author does undermine the typical accounts of the origins of bebop later in the passage, that’s not something that happens in the second paragraph. In addition, the author’s point of view later in the passage is that commercialism was involved in bebop.

(B) captures the purpose we anticipated. The underlined phrase is part of the author’s explanation of the analogy between the other people’s account of bebop’s origin and a view about classical music. The line we’re being asked about is a description of the view about classical music. The author follows up this line by connecting that view to the account of bebop’s origin.

Although the author does criticize the other people’s account of the origins of bebop, that happens in the fourth paragraph, not the second paragraph. In the second paragraph, the author has not yet suggested that the typical accounts of the origins of bebop get anything wrong or are based on inaccurate understandings of anything. So, (C) cannot be the purpose of a line in the second paragraph.

In the second paragraph, the author draws an analogy between a view about classical music and the other people’s account of bebop’s origin. But the author never suggests that something in classical music affected something in jazz. Instead, the author’s point in the second paragraph is that a particular understanding of the origin of modern classical music is similar to a particular understanding of the origin of modern jazz.

The view in the second sentence does not suggest that commercial considerations motivated modern classical music. And, even if it did, the author is simply describing that view, not endorsing it. We don’t know whether the author believes modern classical music was or was not motivated by commercialism.