Detailed Explanation with Core 2 Reference:
Bollards are physical barriers that prevent unauthorized vehicle access to certain areas, providing a preventive measure against unauthorized entry and potential threats. Bollards are classified as a preventive control because they act to deter or block physical access to secured locations, as opposed to video surveillance or alarm systems, which are typically used for detection and monitoring. Core 2 highlights the importance of implementing various physical security controls to protect assets and infrastructure (Core 2 Objective 2.1).