If the drive has a UEFI-bootable boot sector on it, it will show up.  If you don't see the drive in the boot list after pressing F12, it means the drive is not UEFI-bootable. Presumably some of the newer versions of Acronis allow making your own boot media -- alternatively, Macrium Reflect does (including UEFI boot media).  Macrium is generally easier to use than Acronis TrueImage as well.  
I use Acronis True Image to back up my "C" drive. It needs the ability to boot from the USB drive. I am familiar with this process but there is no option to boot from USB in the F12 boot menu on my machine. I am not a wizard when it comes to computer uefi bios. Can anyone explain the process on how to get the USB option to show up in VERY simple terms even I can follow. Thanks in advance. Jim.
How do I get the USB drive option to show in the F12 menu on my Dell Optiplex 
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