This is both cute and funny but the rope creates a literal line and while one can argue that the stripes help create an implied line it is like implying an implied on a literal. My vote is therefore geared towards the composition. 5
I'm not sure what to say about this one. If the line is the rope, then it doesn't meet the challenge because the rope forms an actual line. If the implied line is the line of vision between the dog and the person, then I would have expected to the the dog's eyes.