The author of the passage mentions the Progressives as examples of historians who
saw farmers and small producers as having the potential to become a powerful force in American society
did not question the widespread acceptance of laissez-faire capitalism in the United States, in spite of their sympathy for farmers and small producers
did not agree that religious and communitarian norms were needed to soften the harsh edges of laissez-faire capitalism
saw the development of laissez-faire capitalism in the United States as a historical inevitability, in spite of their lack of sympathy for large capitalists
were somewhat out of the mainstream of the American historical profession
Writing in the early twentieth century, Progressive historians sympathized with the battles waged by farmers and small producers against large capitalists in the late nineteenth century, but they did not question the widespread acceptance of laissez-faire (unregulated) capitalism throughout American history.
原文：Progressive historians sympathized with the battles waged by farmers and small producers against large capitalists in the late nineteenth century, but they did not question the widespread acceptance of laissez-faire (unregulated) capitalism throughout American history.
感觉其他答案都在说一些有的没的，也就是需要你用脑去推断出来的东西(而且这样的推断还有可能不正确)。