Final answer:
The statement is true. Stairs in a three-story residence must be enclosed in a fire-rated enclosure or shaft to prevent the spread of fire and smoke.
Step-by-step explanation:
The statement is true. Stairs in a three-story residence must be enclosed in a fire-rated enclosure or shaft to prevent the spread of fire and smoke. This is important for the safety of the occupants, as it provides a protected escape route in case of fire. The fire-rated enclosure or shaft is designed to resist fire for a certain period of time, giving people enough time to evacuate.