Which permissions are MOST appropriate for files that are publicly accessible but only modifiable by the original owner?

The most appropriate permissions for files that are publicly accessible but modifiable only by the original owner are read and write permissions for the owner, read permissions for the group, and read permissions for others. This means the owner has full control over the file, including the ability to modify it, while group members and all other users can only read the file but not make any changes to it.

In this case, the permission set of read and write for the owner (rw-), read for the group (r--), and read for others (r--) is indeed represented correctly with the choice given. This ensures that while anyone can view the file, only the original owner retains the ability to change or modify its contents, which meets the requirement of the scenario described.

Other permission sets either grant additional write access to groups or others, or limit access too much, making them less suitable for the stated needs.