I think maybe because teens have more pressure in school with their looks and everything. Adults usually become more successful in life after they graduate, I guess. Not all adults do, but it usually helps. If that makes sense.
I hope this help
I believe the appropriate answer is C. not sure though...
2 internal influences is your bones will feel stronger and you will have more energy . 2 externals are you will lose weight and look skinny and your face and skin will look healthy.