Which factor is least important when reviewing plans for construction in a floodplain?

When reviewing plans for construction in a floodplain, the least important factor is the number of bedrooms. This aspect is less critical because it does not directly impact the structure's resilience against flood risk, whereas other factors play a significant role in minimizing flood damage and ensuring safety.

The choice of building materials is vital since certain materials can withstand flood conditions better than others and contribute to the overall durability and longevity of the structure in a flood-prone area. Similarly, the lowest floor elevation is crucial because it determines how high the building has to be to avoid floodwaters, and enclosures below the elevated floor can impact floodwater flow and debris accumulation, which affects the structural safety in floods.

Focusing on the number of bedrooms does not address the essential requirements for floodplain management, which prioritize safety, prevention of damage, and compliance with regulatory guidelines. Thus, while the number of bedrooms may have implications for livability and usability, it does not directly contribute to mitigating flood hazards in the context of construction in a floodplain.