Answer: Option A. -> Slightly acidic medium
:
A
Ptyalin of saliva acts in acts in a neutral or faintly acidic medium (optimally at pH 6.5)

Answer: Option C. -> rennin – casein
:
C
Rennin is the enzyme that acts on casein which is a milk protein. It is secreted by the gastric glands in an inactive form prorennin which is activated by HCI. Rennin converts caesinogen into calcium paracaesinate in the presence of calcium ions. This ensures that milk remains in the stomach as long as possible. The largest amounts of rennin are present in the stomach of young mammals. Carbohydrate, maltose and protein are acted upon by carbohydrase, maltase and protease respectively.

Answer: Option D. -> Small Intestine
:
D
Protein and all other nutrients get absorbed in the small intestine. The digestion process starts in the stomach and continues in the duodenum. The digested protein and other nutrients then gets absorbed.

Answer: Option B. -> Amino acids and glucose
:
B
Glucose and some amino acids are absorbed with the help of the carrier ions like Na+. This mechanism is called the facilitated transport.

Answer: Option D. -> Different cells
:
D
The pancreas is a gland organ in the digestive and endocrine systems of vertebrates.It is both exocrine; (secreting pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including insulin, glucagon, and somatostatin). The beta cells produce insulin, alpha cells produce glucagon and delta cells produce somatostatin. There are two main types of exocrine pancreatic cells, responsible for two main classes of secretions. The centroacinar cells produce bicarbonate ions and basophilic cells secrete digestive enzymes.