Final answer:
The activation of any smoke detector located in an elevator lobby will trigger the alarm to sound.
Step-by-step explanation:
When the activation of any smoke detector located in an elevator lobby occurs, it will trigger the alarm to sound. Smoke detectors in elevator lobbies are designed to detect the presence of smoke particles in the air. When smoke particles interfere with the ions between the metal plates inside the smoke detector, the flow of current is interrupted and the alarm is activated.