This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Digestion and Absorption, Subject name: Physiology
Fecal mass is mainly derived from: 
Select and explain. 
A. Undigested food, B. Digested food, C. Intestinal secretion, D. Intestinal absorption
A: Undigested food
Answer: A: Undigested food 
Explanation: Ans. (a) Undigested foodRef: Ganong 25th ed. / 502* Fecal mass is derived from undigested food.* Feces are the particles of waste matter that is left over after the body has processed and absorbed nourishment from the foods we eat.* It contains water, dietary fiber, inorganic salts, dead cells, bacteria, and anything the body cannot or will not absorb.