Choose the best answer to complete the statement: A 110V smoke _____.

A 110V smoke alarm is the correct choice because it refers to a device that not only detects smoke but also actively alerts occupants of a potential fire situation. Smoke alarms are designed to provide an audible warning, typically through a loud siren or beeping sound, when smoke is detected. This is crucial for safety, as it allows individuals to respond quickly to evacuate or take further action.

The other options don't provide the complete functionality associated with a 110V device in this context. A smoke detector identifies smoke but may not necessarily alarm or alert individuals on its own, while a smoke monitor typically refers to devices that measure smoke levels without the immediate alert functionality of an alarm. A smoke sensor can detect smoke but does not define the alerting mechanism provided by an alarm. Thus, a 110V smoke alarm encapsulates the functionality of detection and alarm, making it the most suitable answer.