Final answer:
The details showing how people responded to the discovery of gold in the Klondike reveal their emotional reactions and support the topic by illustrating the gold rush's influence on individual and community actions.
Step-by-step explanation:
The authors include details about how people responded to the news of the discovery of gold in the Klondike. These details support the topic because they highlight the emotional reactions of people to the news. This is seen in the frenzy and rush to the gold fields and the rapid population growth in California post-discovery, evidencing a direct emotional and action-driven response to the prospect of wealth and opportunity.
Based on the topic of this excerpt, the most relevant supporting detail would be C) The reactions of people in nearby towns to the news of the discovery. These reactions provide insight into the influence and impact that the discovery of gold had on individuals and communities, driving economic and demographic changes within the West.