Since the whole point of a guro choose your own adventure game is to die as often as possible and keep reloading, I'll vote C.

If you want to stick with the two variations you mentioned I'll go with C1, but if you'll permit me another write-in: why repeat an execution method we've already seen when there are plenty of other ways to decapitate someone? For example, the executioner is a big strong lad; if he braces his feet against Natalie's shoulders while they're lying on the ground I imagine that with a bit of effort he could pull her head clean off with his bare hands. And prior to that, our protagonist could have her head slowly removed piece by piece at Natalie's request: first her head is scalped and skinned, then the skull is carefully sawed in two halves which are pulled apart. Next, all remaining flesh and her eyeballs are removed before snapping her brain stem and pulling away her brain. Naturally Natalie asks lot of questions during this, which our protagonist answers verbally at first before switching to thumbs up/down hand gestures when her mouth is gone.

Some alternate methods I haven't really seen used yet in other stories/images:
- Split the head down the middle with an axe, pull apart the two halves and dig out the contents.
- Gradually remove the head by firing three-round bursts at it with an assault rifle, making sure to target non-vital areas first.
- Rather than pulling the head off, pushing it in would also make it look like someone was headless. Keep the torso in place and push the head down between the shoulders and into the rib cage.

In my opinion, SnuffCon would be a perfect place to demonstrate some novel methods of maiming and killing that the guro enthusiasts who visit it aren't familiar with yet, similar to the way new products are launched at tech conventions or how they demonstrate innovative prototypes at car shows. Then again, I know my tastes are a tad unconventional even for the guro community, so if you want to stick to more traditional execution methods that's perfectly fine too.

The edited version seems like a good idea: it makes for a better reading experience for those who want to read it in the future, since they don't have to wade through tons of voting comments. Also, I don't think I recall ever seeing a guro-themed CYOA story, so it would be worth it for the novelty alone.