My cat licked my cheek the other night, about 1am. I have no hair on my cheek, so I don't know if that was an act of grooming me or not. However, the licking woke me up and the biting a hole in my cheek hurt and I was so surpised. I got up, of course..he had food, water, all his toys at his disposal so I'm very confused. Which equation is represented by the graph below_