I've seen 'selvsagt' used in a similar sentence. It makes sense ('self said'), but is it used interchangeably?
They are both used to explain the other in the dictionary, they are interchangeable.
I place selvsagt among the conservative words (in the wild jungle of alternate forms and endings which is Norwegian), I personally prefer radical terms and endings and I actually prefer selvfølgelig, maybe because the other option sjølsagt feels even more radical and borders nynorsk territory.
Self-explanatory = selvforklarende. Which is not the same as obvious although self-explanatory can be pretty obvious. I would rarely use it in connection with "choice" anyhow.