The author of the passage mentions works by Hill and Carnegie most likely in order to

This choice implies that the author is forecasting a future trend regarding self-help books. However, the passage does not indicate any predictions; instead, it focuses on the historical and ongoing significance of such literature, suggesting that the reference to Hill and Carnegie is meant to support an assertion rather than predict future trends.

While the mention of Hill and Carnegie provides insight into the genre, the author is not merely paraphrasing their views. Instead, the author uses these references to bolster a broader claim about the lasting presence and influence of self-help books, rather than summarizing expert opinions.

This option suggests that the author is sharing a personal viewpoint on self-help literature. However, the passage is analytical in nature and relies on external references for support, indicating that the author’s intent is to substantiate a claim rather than express a subjective opinion.