As @Snowflakez said, very true.We can only speculate at the moment, what I do know is that the number of options given in dialogue choices remained more or less consistent throughout CDPR's recent titles (Witcher 2, Witcher 3, Blood and Wine). This may or may not be related to Geralt's character, CDPR's writing/design philosophy, cost related tradeoffs, or other factors.
But one can hope CDPR will take "RPG" to heart and have as many dialog option as are reasonable.
Since (apparently) there's always an option to pull a weapon and start combat that doesn't need to be a dialog option.
So presumably even having 2-3 means "Agree", "Disagree", and "More Information" the the very least. Hopefully there are more then that because I'd say that's obviously the bare minimum.