Interesting question... I don't cheat and this includes reload.
So, when I see a hut I have no way of knowing what it will come out of it.
If there was a way of knowing that entering a hut would give you a city (advanced tribe), obviously I would vote for options C or D.
Choosing between C and D depends on other factors: if you find another CIV very early (close to your starting point) I would advise you to immediately colonize the terrain (building a second city) or they will do it instead. The same if you find very good terrain areas (like Rivers with Hills or lot of special resources, like Coal, Oil and Gold). In these cases, I would choose D.
However, if nobody seems to be near you and the terrain doesn't look that good, then I would suggest keeping the "None" Settler unit as long as you can - build a second city using Settlers produced by the first and then use "None" Settler unit to link both cities by road and paving the way for third, fourth, and so on. [Option C]
However, since there is no way of knowing what the hut will give you, in my way of playing, I would have to opt between A and B.
In this situation, which happens almost every game, I definetely choose B.
Losing a couple of turns or even more in the beginning of the game is easily compensated by getting the most out of your city.