Vitamin B12 is absorbed just before the small intestine joins the large intestine. Bile salts are reabsorbed in the distal ileum and the ascending colon.
Small intestine The small intestine in the adult is approximately 22 feet long and consists of the duodenum, the jejunum, and the ileum. The small intestine wall is arranged in folds of absorptive cells and villi.
Most nutrient absorption occurs in the small intestine including minerals, vitamins, proteins, and fats. Iron, calcium, magnesium, and zinc are absorbed almost immediately after leaving the stomach – ie, in the 8 feet of the duodenum and the jejunum. Sugars and vitamin C, as well as thiamin, riboflavin, pyridoxine, and folic acid, are absorbed in the upper third of the small intestine. Protein is absorbed approximately midway through the ileum. Vitamins A, D, E, and K, fats, and cholesterol are absorbed in the lower third of the ileum.
Answer : (b)