Preference for USB Input

I am installing Audacity for first-time use (in a Windows 8.1 environment) and have arrived at page 8 of the instruction manual where I am directed to designate the recording device as “USB Audio Device”. My dropdown menu for input in the Edit-Preferences menu does not offer this as an option. What should I d?

I don’t know which instruction manual you are reading, but it’s not the Audacity 2.0.6 manual (Audacity Manual)

Do you have Audacity 2.0.6 (see “Help menu > About Audacity”)?

Normally you should connect the USB device and allow Windows a few moments to recognise it before you launch Audacity.
If you start Audacity first, you will need to tell Audacity to “Rescan Audio Devices” after connecting the USB device (see near the bottom of the Transport menu).

More information about recording from USB devices here: Audacity Manual
Note that if you installed Audacity using the recommended installer version, the manual may be accessed via the Audacity Help menu.