Final answer:
The category that best encompasses simple sugars, amino acids, and fatty acids absorbed from the digestive tract is Organic nutrients.
Step-by-step explanation:
The category that best encompasses substances absorbed from the digestive tract, such as simple sugars, amino acids, and fatty acids, is A) Organic nutrients. These are absorbed through the intestinal villi into the bloodstream or lymphatic system, depending on their solubility. Simple sugars and amino acids are typically water-soluble and therefore can be readily absorbed into the bloodstream. Fatty acids, which are lipid-soluble, are absorbed along with dietary lipids in micelles and transported through the lymphatic system. Organic nutrients provide the body with energy, serve as building blocks, and are involved in regulating body processes.