Perhaps the most "cost-effective" shot of the challenge. Simple (sometimes a euphamism for 'so little effort involved'), mono, and graphic. Required merely recognition of the pattern as pretty and then a snap. Not that I am a critique... I admire such results from such economic action. ;-)
Very very nice study in gradients. I like it a lot. But the lines don't really lead to anything and are the subject themselves. In that respect and IMO DNMC. A better entry for the abstract macro challenge maybe?
I really like looking at this, however the lines don't really lead my eye into (or away from) a particular point, which IMO is the purpose of this subject.