These are the options in grub menu
e- edit commands before booting, c- command line, a- modify the kernel arguments before booting.
Select 'e'…..
root (hd0,0) kernel /vmlinuz-2.4.20-6 ro root=LABEL=/ initrd /initrd-2.4.20-6.img
which of the following add the “single' or '1'. kernel /vmlinuz-2.4.20-6 ro root=LABEL=/ 1