Answer:
Internal can be you don't want bad things happening to your body, you don't want drugs affecting your health,etc.External could be you don't want it to affect your family or people around you.For example, like a cigarette if you are smoking in public you can be affecting others passing by or hanging out with you(external)but if it's just you by yourself smoking it is damaging your lungs(internal)
The thyroid gland... I think
D. heart disease because of all the fats in the food
People with a higher basal metabolic rate
:):):)
because they burn calories faster, thus they need more
