Device for boot loader installation via USB

Question

I have used Ubuntu before, and really enjoyed using it, but it was set up by a friend of mine in the computer science department of our university, and we were making a dual-boot out of my netbook. Now, however, there is a different sort of problem. My home-base computer is a rather old mac book pro, and instead of dual-booting that, what I want to do is make my USB a bootable copy of Ubuntu. However, when I go to install it on the correct drive device, I am asked to choose "Device for boot loader installation," and I do not know which one to choose. I have found that it is much easier to do this initial installing on a PC, so I am using the ones that my University provides for students to use, but I do not want to break the computer's functionality since I might have to pay for it and I a rather broke grad student.

The current break down of my options:

/dev/sda /dev/sda1 ntfs 
/dev/sdc and /dev/sdc1 fat32  

The sda drives are the SATA drive for my school computer and the sdc drives are the one that I want to install ubuntu to.

Solution

/dev/sdc is your usb drive. If you want to install ubuntu in usb drive then select "/dev/sdc1" for your ubuntu operating system installation and for bootloader installation select "/dev/sdc". Keep in mind /dev/sdc1 for os installation and /dev/sdc is for bootloader installation. In this way your pc hard disk will be untouched and ubuntu will be totally installed to usb.