Which of the following best describes the term “data breach”?

The term "data breach" is best described as unauthorized access to confidential information. This definition highlights the core aspect of a data breach, which involves individuals or entities accessing sensitive data without permission. Such access can compromise the confidentiality, integrity, and availability of the data, often leading to serious repercussions for individuals and organizations, including identity theft, financial loss, and damage to reputation.

In contrast, other choices refer to different scenarios. A hardware failure resulting in data loss pertains to physical issues with storage devices rather than security breaches. A failed software update refers to issues with the software update process and does not involve unauthorized access. Lastly, the installation of new security features deals with enhancing security measures rather than a breach occurring in the system. These alternatives do not capture the essence of what constitutes a data breach.