What is a primary function of smoke detectors in fire alarm systems?

The primary function of smoke detectors in fire alarm systems is to detect the presence of smoke and alert occupants. Smoke detectors are designed to sense smoke particles in the air, which typically indicate a fire is present or imminent. When smoke is detected, these devices activate the alarm system, providing critical information and alerting people in the vicinity to evacuate or take appropriate actions to ensure their safety. This early warning helps to minimize the risk of injury or loss of life by giving occupants vital time to respond to the threat.

Other options, while relevant to fire safety, do not represent the primary function of smoke detectors. For instance, controlling fire doors and communicating with sprinkler systems are actions that may complement fire safety efforts but are not the direct purpose of smoke detectors. Additionally, providing an emergency exit strategy involves planning and signage rather than the direct detection of smoke, which underscores why option B is the most accurate choice in this context.