What does the term "security breach" mean?

The term "security breach" refers specifically to an incident where unauthorized individuals gain access to sensitive or confidential information, such as personal data, financial records, or proprietary corporate information. This can happen through various means, such as hacking, phishing, or insider threats. The key aspect of a security breach is that it involves a violation of the expected security protocols and allows unauthorized access, which can lead to data loss, data theft, or compromise of the system's integrity.

The other options describe different security-related activities but do not encapsulate the essence of a security breach. Upgrading security measures refers to enhancing protections before a breach occurs, while successfully preventing a cyber attack focuses on defense mechanisms rather than the actual event of a breach. Conducting routine inspections of security protocols is a proactive measure aimed at identifying vulnerabilities but does not imply that a breach has occurred. Hence, option B accurately captures the meaning of a security breach, making it the correct answer.