what is Nr1,Nr2??

Another question is like what do you mean by Nr 1 best structure how can we defend that
Nr 1 best structure Download structure
Nr 2 best structure Download structure
Nr 3 best structure Download structure
Nr 4 best structure Download structure

These are simply the top4 ranked models. Nothing more. And they are provided for each cluster.

Never but on a single model, do look at multiple models and consider various clusters, especially if they score is overlapping when considering their standard deviation