Which of the following is the BEST way to enable User12 to use the directory without letting other users manipulate its content?

A technician created a new directory for use by a user "User12". User12 is unable to create new files or subdirectories within this new directory. Using the ls command, the technician observes the following:

drwxr-xr-x 2 root root 4096 May 24 13:11 dirname

Which of the following is the BEST way to enable User12 to use the directory without letting other users manipulate its content?

A.
chown dirname User12

B.
chmod 700 dirname

C.
chown User12:User12 dirname

D.
chgrp User12 dirname