Answer: The correct command to set "other" permissions on a file to r-x is:
chmod 755 file
In this command, the first digit (7) sets permissions for the owner, the second digit (5) sets permissions for the group, and the third digit (5) sets permissions for others.
The number 7 in the first digit indicates that the owner has read (4), write (2), and execute (1) permissions (4+2+1=7). The number 5 in the second and third digits indicates that the group and others have read (4) and execute (1) permissions (4+1=5). Therefore, the command chmod 755 file sets the permissions on file to -rwxr-xr-x, which means the owner has read, write, and execute permissions, and the group and others have read and execute permissions.
Explanation: o