You can select LILO destination here. There are three options:

• Root - Store in the superblock of your root Linux partition.
• Floppy - Store in the traditional floppy.
• MBR - Store in the master boot record of the first hard drive.

My personal choice always be the MBR. That's not a safe choice if you share Linux with Windows or other operating system (though I never have problem here).Floppy would be a little hassle. Furthermore, not many modern computer has a floppy drive anymore. The root partition is also not a bad choice. Slackware mention about setting up a bootable partition later with fdisk to whatever partition you chose here. However from my experience, that is not needed. Slackware can boot successfully without setting up the boot flag earlier or later. If you have problem booting up later, then, boot with usb boot device we created previously and activate boot flag for the partition you choose here.