How do you arrive to the right answer

Hi Audrey, thanks for the question! What C is saying is that perhaps this athlete's experience isn't useful to determine what other people's experiences will be. For this reason the argument would be flawed in concluding heating pads are more effective than stretching because maybe this athlete is just the odd one out for whom heating pads are unusually useful. The reason A is wrong is because the argument only made a conclusion about which method is better at relieving lower back pain. It made no judgments about which method would be better to heal the underlying injury and therefore it isn't a flaw that it overlooked this. I hope this helps. Please let me know if you have any other questions or if you'd like me to elaborate further!