Which commands would accomplish that?

You want all users in the group ‘operators’ to be able to mount and unmount filesystems and nobody else. Which commands would accomplish that? (choose the best 2 answers)

A.
chgrp operators /sbin/*mount; chmod 1750 /sbin/*mount

B.
chgrp operators /sbin/*mount; chmod u+s,o-rwx /sbin/*mount

C.
chgrp operators /sbin/*mount; chmod g+s,o-rwx /sbin/*mount

D.
chgrp operators /sbin/*mount; chmod 4750 /sbin/*mount

Explanation:
The chgrp command is used to change the group that has access to files and directories. All files in linux belong to an owner, and a group. The owner is set by the chown command, and the group by the chgrp command.

The chmod changes the permission of a file:
-R, –recursive change files and directories recursively

Permissions
u – User who owns the file.
g – Group that owns the file.
o – Other.
a – All.
r – Read the file.
w – Write or edit the file.
x – Execute or run the file as a program.

Numeric Permissions:
CHMOD can also to attributed by using Numeric Permissions:

400 read by owner
040 read by group
004 read by anybody (other)
200 write by owner
020 write by group
002 write by anybody
100 execute by owner
010 execute by group
001 execute by anybody