A squirrel descends an 8-m tree at a constant speed in 1.5 min. It remains still at the base of the tree for 2.3 min. A barking dog then causes the squirrel to scamper partially up the tree in 0.03 min to approximately one-third from which it started. Ignoring speeding up and slowing down motion, which graph most closely represents the squirrel's vertical displacement from the base of the tree