The database that keeps student project grouping information is stored in a file on a ECS server. % ls -1 groups.db ?????????? 1 joe student 827 Nov 29 15:01 groups, db The file should be able to be edited by the grader Joe, scripts running as students (in group student should be able to do lookups, and the professor (not in group studet ) should be able to check it. But students should not be allowed to change the database themselves. Which of these would be an appropriate permission mode for the file (replacing the question marks)? 04755, -rwsr-xr-x O 00644, -rw-rw-r-- 00644, -rw-r--r-- O 00777. -rwxrwxrwx O 00640, -rw-r