In which organ of the digestive system does most of the digestion and absorption occur? A. Mouth
B. Stomach
C. Large intestine
D. Small intestine

D

Explanation:

The small intestine is where the most digestion and absorption occur.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.