Horned lizards use their horns to defend against predatory birds. A researcher observed that lizards living in areas with predatory birds have longer horns than those in areas with no predatory birds. This observation led her to hypothesize that longer horns offer more protection against predation than do shorter horns. To test this hypothesis, the researcher tagged 20 lizards with long horns and 20 lizards with short horns in each of two locations: Desert Valley, where there are no predatory birds, and Cactus Corner, where there are predatory birds. She returned every week for 12 weeks to measure survival of tagged lizards. The graphs below represent her findings. What can you conclude from the researcher's results