Final answer:
When the girl is at the highest point of her jump, all of her kinetic energy has been converted to potential energy.
Step-by-step explanation:
When the girl is at the highest point of her jump, all of her kinetic energy has been converted to potential energy. At this point, her velocity is zero and she has reached the maximum height of her jump. Once she starts descending, potential energy is gradually converted back into kinetic energy as she gains speed.