Medical researcher: Scientists compared a large group of joggers who habitually stretch before jogging to an equal number of joggers who do not stretch before jogging. Both groups of joggers incurred roughly the same number of injuries. This indicates that stretching before jogging does not help to prevent injuries. Which one of the following, if true, would most weaken the medical researcher's argument? ['Most jogging injuries result from falls, collisions, and other mishaps on which the flexibility resulting from stretching would have little if any effect.', 'For both groups of joggers compared by the scientists, the rate of jogging injuries during the study was lower than the overall rate of jogging injuries.', 'Studies have found that, for certain forms of exercise, stretching beforehand can reduce the severity of injuries resulting from that exercise.', 'The more prone a jogger is to jogging injuries, the more likely he or she is to develop the habit of performing stretches before jogging.']