Final answer:
Excerpt C best conveys the theme that rebuilding is achievable through unity, highlighting the importance of collective action over individual efforts in the context of reconstruction after a disaster.
Step-by-step explanation:
To convey the theme that rebuilding is achievable when people unite after a devastating event, the best excerpt from "The Great Fire" would be:
C) "Individual efforts were futile in the face of disaster, but collective action sparked a resurgence of hope and reconstruction."
This excerpt clearly emphasizes the power of unity and collaboration in the face of adversity. The key idea here is that while individual attempts might be overwhelmed by the scale of a disaster, collective action both embodies and inspires hope, ultimately leading to successful reconstruction. The excerpt captures the essence of a community coming together to overcome a challenge, which aligns well with historical examples of societies rebounding from catastrophes through communal effort and adaptability.