19. In context, the metaphor in the third sentence ('it was... years') chiefly serves to:

Answer: D

Explanation:

Place the Lewis and Clark expedition into a broad context

The metaphor in the third sentence emphasizes the extensive history of the West prior to the Lewis and Clark expedition, illustrating that their journey was just a small part of a much larger narrative. This context highlights the significance of the region's history that existed long before the explorers arrived.

A) Call attention to the age of the United States as a nation

This option is incorrect because the metaphor focuses on the deep historical roots of the West rather than emphasizing the relatively recent establishment of the United States. It does not serve to highlight the age of the nation itself.

B) Question the literary value of the writings by Lewis and Clark

This option is not supported by the metaphor. Instead of questioning their literary value, the metaphor contextualizes their writings within a larger historical framework, acknowledging their contributions while recognizing the existing history of the region.

C) Trivialize the accomplishments of the Lewis and Clark expedition

While the metaphor does suggest that the expedition was a small part of a greater history, it does not necessarily trivialize their accomplishments. It instead places them within a more complex narrative, recognizing their explorations as significant but not the sole contributors to the history of the West.

D) Place the Lewis and Clark expedition into a broad context

This option is correct as the metaphor illustrates the extensive history that predated the Lewis and Clark expedition, effectively situating their journey within a larger narrative of the West. It highlights that the expedition was only a subplot in a much richer historical tapestry.

Conclusion

The correct answer, D, effectively captures the essence of the metaphor by acknowledging the broader historical context in which the Lewis and Clark expedition occurred. Options A, B, and C fail to recognize this broader perspective, focusing instead on aspects that do not align with the intent of the metaphor. Thus, D stands out as the most accurate interpretation of the sentence's meaning.