excretory system: removes waste from blood.
respiratory system: obtains oxygen so the energy in the nutrients can be extracted.
circulatory system: transports nutrients from small intestine to the othet tissues.
nervous system: regulates and controls digestive functioning.
( Am not completly sure, but i think this is the answer)
I would have to say Proteins, lipids, and carbohydrates. Carbohydrates being the first energy source, lipids second and lasting the longest, and proteins the third and final source. although you did not give the full question, so i do not know if i can be completely sure.
