I think the answer to this question is headache. <span />
This actually depends on which level of education you are and what they are looking for. Most people though merely considers it a part of the Digestive System as the bile it stores is used during digestion.
I have seen however several people put it down as part of the bilary system or subsystem which responsible for the creation and distribution of bile.
If i’m not wrong the main macronutrients are fats carbs and protein, i don’t know if that’s for teens but those are the main macros
Answer:
C. Calcium and phosphorus
Hope this helps!