What is the primary purpose of a burglar alarm system?

The primary purpose of a burglar alarm system is to detect unauthorized entry and alert the property owner or authorities. This function is fundamental to security systems, as they are specifically designed to protect properties from theft, vandalism, or other intrusions. When an alarm is triggered due to unauthorized access, it serves to immediately notify the relevant parties, which can include the property owner and law enforcement, allowing for a timely response to prevent potential loss or damage.

The other options, while they may be functions of various other systems or features, do not align with the core objective of a burglar alarm. Monitoring temperature and humidity is more relevant to environmental control systems rather than security. Providing surveillance through cameras is a different category of security measure that complements burglar alarms but is not its main purpose. Controlling a building's lighting system is related to energy management or home automation and does not pertain to detecting intrusions. Thus, the focus on detecting unauthorized entry clearly defines the primary function of a burglar alarm system.