Final answer:
The best description of the theme is the importance of fireproof buildings and preparedness in sparing certain structures from destruction during massive fires.
Step-by-step explanation:
The theme of the paragraph is best described by the statement that certain buildings were spared because they were fireproof. The selected paragraphs highlight the destruction caused by massive fires, the loss of life and property, and the importance of building materials and construction practices in preventing such catastrophic damage. Fires that ravaged cities led to innovations in building requirements, including the use of brick and steel, which are less flammable than wood. This theme addresses how preparedness and the use of fire-resistant materials can significantly impact the outcomes of such disasters.