Final answer:
The untrue statement about the gastrointestinal tract is that villi are present within the large intestine, which is incorrect; villi are found in the small intestine.
Step-by-step explanation:
The statement about the gastrointestinal tract that is untrue is: B. Villi present within the large intestine take in water as well as mineral salts. Villi are not present in the large intestine; they are a feature of the small intestine where they play a crucial role in nutrient absorption by increasing the surface area. Villi contain lacteals, which are lymphatic vessels that absorb dietary fats. The large intestine primarily absorbs water, leftover salts, and some vitamins but does not have villi or enzymatic activity. The ileum, part of the small intestine, is responsible for the absorption of vitamin B12 and bile salts, aiding digestion.