Which of the following files should the administrator edit in order to change the default system run

A Linux administrator just installed Xfree86. Which of the following files should the administrator edit in order to change the default system runlevel from 3 to 5?

A.
/etc/inittab

B.
/etc/runlevels

C.
/etc/rc.sysinit

D.
/etc/defaultrunlevel