A Linux system administrator needs to allow a user named 'johndoe' to have read and write access to a file called 'report.txt', which currently does not grant him those rights. The administrator does not want to modify the existing group permissions on the file. Which command should the administrator use to achieve this without affecting the rights of other users?
usermod -a -G report.txt johndoe
chown johndoe: report.txt
chmod u+rw johndoe report.txt
setfacl -m u:johndoe:rw report.txt