Answer :
Lactase is an enzyme that plays a crucial role in the digestion of lactose, which is the sugar found in milk and dairy products. It works by breaking down lactose into two simpler sugars: glucose and galactose, which can then be absorbed into the bloodstream.
Lactase is located in the brush border of the small intestine. The brush border is the microvilli-covered surface of the small intestine's epithelial cells. These microvilli increase the surface area of the small intestine, aiding in more effective digestion and absorption of nutrients.
When you consume dairy products, lactose reaches the small intestine, where lactase is present in the brush border. The lactase enzyme facilitates the hydrolysis of lactose into glucose and galactose, which are then easily absorbed into the blood.
The other options in the multiple-choice question, such as saliva, gastric juice, and pancreatic juice, do not contain lactase. Saliva and gastric juice are involved in different initial digestion processes, while pancreatic juice contains other digestive enzymes but not lactase. Therefore, the correct choice is C. Brush border of small intestine.