Which command would you use to check the filesystem for errors in Linux?

The command used to check the filesystem for errors in Linux is indeed the one that stands out as the correct option. It stands for "File System Check." When executed, it scans the specified filesystem for inconsistencies and potential issues, allowing for repairs in cases where errors are found. This command can be particularly useful before remounting a filesystem, ensuring that it is in a healthy state.

The other commands listed serve different purposes. For example, one command is typically used to report filesystem disk space usage, and another command is primarily focused on mounting filesystems, which involves making a storage device accessible at a specified mount point within the filesystem hierarchy. The fourth command is specific to retrieving information about XFS filesystems, which is more about reporting than checking for errors. Thus, the unique functionality of checking for and potentially fixing filesystem errors clearly establishes the correctness of the selected command.