To determine which starting position allows every car to complete the loop, Peggy needs to assess if each car can successfully navigate the loop from various heights. The best experiment to achieve this goal is:
A. an experiment where Peggy drops each car from different starting heights multiple times and records which heights allow all three cars to complete the loop every time.
This option directly addresses the need to find the specific heights that enable all three cars to successfully complete the loop, providing comprehensive data on which starting heights are effective.