What is a "security breach"?

A "security breach" refers to an incident where unauthorized access to secured information or areas occurs. This definition captures the essence of a security breach, highlighting that it involves the compromise of information security or physical security measures put in place to protect assets, data, or facilities.

In this context, the key components of a security breach are the unauthorized access and the nature of the access being related to secured information or restricted areas. Such breaches can lead to data theft, loss of sensitive information, or physical threats to individuals and property, making them a critical concern in security practices.

The other choices do not appropriately define a security breach. For instance, the absence of a security officer could lead to vulnerabilities but isn't, in itself, classified as a breach. Additionally, an alarm being triggered could signal a breach, but without further context, it does not define one. Lastly, visibility obstruction may pose risks in security, but it doesn't equate to unauthorized access or compromise of secured information, which is the core of a security breach.