What is the purpose of fire partitions in a building?

Fire partitions play a crucial role in fire prevention and safety within a building. They are designed primarily to limit the spread of fire and smoke between different areas or compartments of a structure. The correct option highlights that fire partitions extend from the floor to the underside of the floor above, creating a barrier that effectively confines fire and smoke, thus protecting occupants and allowing for safe evacuation.

This vertical continuity from the floor to the ceiling or the floor above is essential for maintaining the integrity of the fire barrier, as any gaps might allow fire to breach the partition and spread, defeating its purpose. Other options, while they might pertain to aspects of building construction or safety, do not accurately reflect the primary function of fire partitions in maintaining compartmentalization during a fire event.