A few points: AF-S is for still subjects and she is obviously moving forward, the most difficult to maintain in focus of movement directions. High ISO reduces detail so it is hard to say if her hand is really out of focus, some of the detail of edges are not seen because of the ISO being high. The leaves appear more detailed because they have distinct edges and give the illusion of sharpness. Of the 3, only the last has obviously missed focus. Burst in AF-S means re-acquiring focus lock each time the mirror comes back down. AF-C, has tracking hysteresis which tries to predict where the subject will be during the black out period when no focusing can be accomplished. The last point I wanted to mention was the focus point, it is larger than the box outline in the VF so you have to be careful to keep a high contrast focus target dominating the box with overlap. Her hand was anything but a high contrast target. Considering the variables that were in play, 2 of the frames are OK.