Problem: A 15-year-old boy presents for a routine health examination. A review of systems is positive for occasional nocturnal aches in his thighs, which usually resolve by morning. He actively participates in voluntary outdoor service activities and says he would like to begin more vigorous-intensity exercises. What is the most appropriate recommendation? Need Assignment Help? A. Engage in enjoyable, moderate to vigorous physical activity without limitations. B. Gradually increase the amount of physical activity over several weeks. C. Engage in mostly vigorous-intensity exercises (up to 85% of aerobic capacity). D. Limit intense exercise that may exacerbate the leg pain.