I think it fits the Challenge nicely.
I had a hard time counting the rings originally, and still again this second time, whether it's all that oil from the chain saw or the lighting that was used.
It's a very unusual cut of wood, different shape towards the right hand side as you look at it.
I like the various colours of the wood that you were able to capture, and it is slightly out of focus, once again perhaps due to the excess oil/wet darkness not allowing a good sharpness to the centre or the fuzzy bark and end cuts.
I think you were also a bit quick with your cropping the way you cut off the bottom of the log so sharply.
I had intrepreted the challenge to show a physical number, not something that we had to count. With that in mind, I definately see a 0 here. :) While the focus and clarity are good, I think that the lighting was a bit harsh for you. There are a couple bright spots that almost wash out the subject in some places. mainly to the bottom right. the angle and framing/cropping are good. I think that I like how you have filled the entire photo with the subject. Good luck in the challenge.