Why can't I choose a harddisk to re-install from?

Unless you have updated your systems firmware & HD with the needed recovery services (onboard or Internet) you may not be able to do the recovery option. Here is the Apple T/N on the Startup options as reference: Startup key combinations for Mac.

You'll need to first download from the Apps store the OS-Installer from a Mac system and do one of the following:

• If you have access to a second Mac and the needed cable you could setup your MacBook Pro in Target Mode: Share files between two computers with target disk mode.
• Using a second Mac prep up an external drive which you can then boot up from. The easiest is a USB Thumb drive (16GB or larger)
• Using the OS installer that came with the system to boot up with (CD/DVD or USB Thumb drive).

Using Disk Utility from the working system delete the partitions on your internal drive so the OS installer is able to create the recovery partition. If you are creating a UDB thumb drive make sure its setup with GUID and create a Mac OS Extended (Journaled) partition. Next create a copy of the OS installer for safe keeping. Run the OS installer to install the OS on either your internal or the USB thumb drive.

>> If you are using the thumb drive: Once done copy the OS installer onto the thumb drive shut down the system and carry the thumb drive to your system to boot up from. Then run the OS installer to install a fresh copy of OS onto your drive. Don't forget to delete all of the partitions beforehand so the installer can create the recovery partition.

Once the system is booting follow this Apple T/N: About EFI and SMC firmware updates for Intel-based Mac computers. That should finish setting you up with both recovery methods. Frankly, I prefer the bootable USB drive ;-} its quicker and I can run Disk Utility to fix minor issues. I also setup other thumb drives with other utilities to address different issues.