Deck footing 2" above the ground -does that apply to a patio? What is the reason behind the 2" restriction?
"C" is the way to go - it has cleanest look.  The point of raising the concrete is to prevent the end grain from wicking moisture and rotting - the concrete is NOT going to deteriorate (unless its mixed poorly and not allowed to cure correctly).  Generally, you don't want wood engaging the ground, nor do you want it sitting directly on concrete.  We separate sill plates all around building foundation walls with foam because the sills will wick from the concrete and rot. Raising the concrete is not the only way to solve the problem... take preventative steps to limit/reduce/stop water from wicking.  Raise the bottom of the wood so it doesn't sit directly on the concrete.  https://www.strongtie.com/capsandbases_woodconnectors/category

We put fences in the ground all the time.  They don't rot (because preventative measures are taken), or do so over an extended period of time.  We don't want the column rotting, but we aren't sticking it in the ground either.  Your detail shows it sitting flush with crushed gravel.  I would dip the end in post preservative or better yet coat it with tar. I'd use a simpson product to keep it off of the concrete (I like the stand off post bases), but keep it below the paver.