As Apple suggests, Mac running OS X Lion v10.7.3 or later should be able to boot from Time Machine backup disk. I followed the instructions on this page https://support.apple.com/en-us/ht202796. I hold down option key while it was turning on, the startup manager popped up but for some reason I didn't see an EFI boot option. The Seagate external drive used for backup is formatted to HFS+ encrypted. My MacBook Pro from late 2011 is running lion 10.7.5. I've tried to press command shift option period and that didn't work. Does anyone have any idea why it's not picking up the Seagate as a bootable drive? The disk utility actually states it's bootable.