D. He should perform rehabilitation exercises, because he his body has gone 3 weeks without the same routine, and therefore he may be more vulnerable to injury.
C. A 50% oxygen saturation level of blood returning to the lungs might indicate an activity level higher than normal.
You can work in the medical field, become a teacher or coach
Stay rested and dont work to much a lot eat healthy and stay hydrated
Skin color would be a good indicator...
