All of the "multiple choice" options are presented as, and announced as being, radio buttons.   Using the r quick navigation shortcut I can cycle through each and every choice.  If I need to go back SHIFT+R runs through the radio buttons in reverse.  I then use the b quick navigation shortcut to go straight to the back, then next, button to move along to the next question.

When I get to the section with videos, things get a bit trickier after the video as there are clusters of scenario statements each of which is followed by a group of radio buttons with answers that gauge your feeling about what the statement said.  I had to occasionally do some switching between conventional navigation and object navigation when I needed to go back a bit, particularly from the radio buttons to the scenario statement, and I could get the statement to read with num pad +.   You also find that there are times when you somehow get into focus mode on those radio buttons, and then quick navigation doesn't work until you hit NVDA+Space to toggle back into browse mode.

I didn't go all the way to the end, but just through the first section and first video.  They seem to be fairly consistent in using buttons for primary controls and radio buttons for multiple choices.
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Brian - Windows 10 Pro, 64-Bit, Version 1809, Build 17763  

The color of truth is grey.

           ~ André Gide