Which of the following is a passive security measure?

Passive security measures are those that are designed to deter or prevent unauthorized access or harmful actions without active intervention or direct action from security personnel. They function by creating physical barriers or environmental conditions that hinder or limit potential threats.

In this context, security lighting and barriers serve as a deterrent to potential intruders. For example, well-lit areas make it difficult for someone to engage in illicit activities without being seen, while barriers such as fences and walls physically restrict unauthorized access to certain areas. These measures actively influence the environment to enhance security but do not require ongoing human involvement to maintain their protective capabilities.

In contrast, surveillance cameras fall under active security measures because they require monitoring, analysis, and response to any suspicious activity captured on video. Regular patrols and undercover operations also necessitate human intervention and proactive engagement with potential threats, which does not align with the passive nature of the correct answer.