Would some of you gurus please opine on these 3 approaches? More specifically, what are the differences, along with the pros and cons of each.
Thank you.

 

Not a guru by any means, but the o-rings are stainless and go between the head and gasket, or block and gasket. Fire-rings are the next step up - they are mild steel and mate against the block and head (gasket water-jetted out). C-rings are different in cross-section - c-shaped instead of round, with the theory being that more boost pushing against the ring will actually increase the sealing power.
Chris