Basically, you want to keep your pages and their permalink structure.
So, C, D, E, F, G - are excluded.
As for B, could be a viable solution, but it depends on your WP permalinks:
1. If your URLs are like: domain.com/category/post.-name.html - you can assign a new category to your post (like "Sold Machines") but your URL will change:
domain.com/unsold/post.-name.html -> domain.com/sold/post.-name.html
2. If your permalinks are like: domain.com/post.-name.html - B is a good option.
A is ok for your users. When someone searches for some king of machine, it is disappointing to find one that has been sold, so it's nice to offer them alternatives.
So, mixing A with B (if possible) is the way to go.
Moreover, B permits you make use of some nice category based widgets like "Just sold" or "New arrivals" etc.

