Appropriate Permissions for Publicly Accessible Files

A.

The most appropriate permissions to set on files required to be publicly accessible but only modified by the file's original owner are option B: r--r--r--.

The permissions are represented by ten characters, where the first character represents the file type, the next three characters represent the permissions for the file owner, the next three characters represent the permissions for the group owner, and the last three characters represent the permissions for everyone else.

In option A: rw-rw-r--, the file owner and group owner have read and write permissions, and everyone else has read permissions. This would allow anyone to modify the file, which is not the desired outcome.

In option C: rwxrwxr--, the file owner and group owner have read, write, and execute permissions, and everyone else has read and write permissions. This would allow anyone to modify the file, which is not the desired outcome.

In option D: rwxrwxr-x, the file owner and group owner have read, write, and execute permissions, and everyone else has read and execute permissions. This would allow anyone to modify the file, which is not the desired outcome.

Option B: r--r--r--, however, gives the file owner read permissions and write permissions, while everyone else has only read permissions. This ensures that only the file owner can modify the file, while everyone else can still access it. This is the desired outcome for files that need to be publicly accessible but only modified by the file's original owner.