Duodenum as the site of enzymatic and alkaline digestion

Steps:

• Identify the gland secreting enzymes for proteins (proteases) and starch (amylase): the pancreas.
• Note the delivery site for these enzymes: the duodenum, first part of the small intestine.
• Confirm alkaline secretions from another gland: bile from the liver (via gallbladder) enters the duodenum to neutralize acid and aid digestion.
• Verify presence of peristaltic muscles: the duodenum has smooth muscle layers for mixing and propulsion.

Why A is correct:

• The duodenum receives pancreatic enzymes for protein/starch digestion and hepatic bile for alkalinity, per standard gastrointestinal anatomy.

Why the others are wrong:

• B (stomach): Secretes only pepsin for proteins, no starch enzymes; acidic, not alkaline.
• C (jejunum): Lacks direct pancreatic/liver duct entry; mainly absorption site.
• D (ileum): Focuses on bile acid reabsorption and vitamin uptake, not initial enzyme digestion.

Final answer: A