Bob, of mass m, drops from a tree limb at the same time that Esther, also of mass m, begins her descent down a frictionless slide. If they both start at the same height above the ground, which of the following is true about their kinetic energies as they reach the ground? A) Bob's kinetic energy is greater than Esther's. B) Esther's kinetic energy is greater than Bob's. C) They have the same kinetic energy. D) The answer depends on the shape of the slide.