Answer:
Pushups
Step-by-step explanation:
You lower and push against your own body weight in push ups, which it the most effective excercise if she wants to use her body weight.
Lifting weights is not her body weight, sprints is just running, and jumprose is simply jumping.
You could argue that because of gravity, it would be harder to jump in jump rope if you weigh more, but thats a technicality, and the best answer is most definetely push ups.