If an intruder smashes the back window of a house and gains entry, triggering an alarm due to motion detection, what category of security measure does the alarm system fall under?
A security alarm system of this nature is considered a detective control because it detects the presence of an intruder and sounds an alarm.
Wikipedia
Security controls are safeguards or countermeasures to avoid, detect, counteract, or minimize security risks to physical property, information, computer systems, or other assets. In the field of information security, such controls protect the confidentiality, integrity and availability of information.
Systems of controls can be referred to as frameworks or standards. Frameworks can enable an organization to manage security controls across different types of assets with consistency.