Which of the following accurately defines a smoke alarm?

A smoke alarm is best defined as a device that detects smoke and serves to alert occupants to potential fire dangers. The correct choice highlights that it is an alarm responsive specifically to smoke. This characteristic is crucial because smoke alarms can operate independently, meaning they do not necessarily need to be connected to a centralized fire alarm system to provide their primary function of detecting smoke and warning individuals of a potential fire.

The distinction in functioning is important; while many smoke alarms can be part of an integrated fire alarm system, there exist standalone units that are designed to operate independently, especially in residential settings. Hence, option B accurately captures the essence of what a smoke alarm does.

Additional details like detecting heat or being installed only in commercial buildings do not define a smoke alarm. Therefore, the focus on smoke detection and the potential for functioning autonomously from a broader fire alarm system encapsulates the key aspects of what makes the correct choice valid.