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?