The correct option is A Stomach - Secretin
The entry of gastric acid inside the intestine triggers the S cells of duodenum to release secretin. Secretin acts on the exocrine part of the pancreas and stimulates the secretion of water and bicarbonate ions.
Cholecystokinin is released by the endocrine cells of the upper small intestine. It stimulates the secretion of pancreatic enzymes and bile juice.
Atrial natriuretic factor is secreted by the atrial wall of the heart. It causes the dilation of the blood vessels, which results in a decrease in blood pressure.
Adrenaline is secreted from the adrenal medulla during emergency situations and so is also called the emergency hormone or the hormone of fight or flight.