Which of the following backups includes only files that have changed since the last full backup?

The correct answer is incremental backup. This type of backup is designed to capture only the files that have changed since the last full backup. By doing so, it optimizes storage space and reduces the time required to perform each backup session, as only new or modified files are included. This can be particularly advantageous in environments where data changes frequently, allowing for quicker backups and easier recovery.

In contrast, a full backup involves copying all files, which can take significantly longer and require more storage space. A differential backup includes all files that have changed since the last full backup, meaning that it grows larger with each subsequent differential backup until the next full backup is taken. A mirror backup creates an exact copy of the data at the time of backup, which can omit older versions of files if they have been changed or deleted since the last backup, rather than just focusing on changes since the last full backup. These differences are key in understanding how incremental backups function within the larger context of data management and recovery strategies.