The author never suggests that progress resulted from commercial pressures. Although she thinks bebop musicians were still influenced by commercialism, and attempted to engage with commercialism, that doesn’t mean that commercial pressures caused the developments of bebop. So the author never uses (A) in the course of her argument.

In addition, even if the author believes commercialism caused the development of bebop, that doesn’t mean the author used the principle that progress is “generally” the result of commercial pressures. That would at most support the principle that artistic progress “is sometimes” or “can be” a result of commercial pressures.

The author never suggests that bebop (or any other new movement in music) started by rejecting fundamental principles of the previously reigning musical style. Although the third paragraph does mention that bebop “shed” jazz’s associations with dance, popular song, and entertainment, we don’t know that those components were part of the “fundamental principles” of swing. Keep in mind, too, that the third paragraph is the author’s characterization of the typical accounts’ view. It’s not clear that the author agrees that bebop shed those associations.

Also, the author never uses a principle about what is “typically” true about new movements. Bebop would merely be a single example of a new movement. The author never argued, “Since bebop is a new movement, it probably rejected the fundamental principles of swing.”

First-hand accounts? The passage never refers to first-hand accounts of musicians and never comments on the kinds of sources historians should use.

The author uses this principle in P3. The phrase “billion-dollar rut” is one of the phrases used by historians in the first paragraph. The author analyzes that phrase to conclude something about the beliefs of those historians.

The author doesn’t comment on music historians’ “aesthetic preferences,” which refers to the artistic features or styles that the historians like. Although the author does say that the typical accounts of bebop’s origin may “suit the needs of contemporary jazz discourse,” the needs of contemporary discourse do not clearly encompass one’s artistic tastes.