Gall bladder contraction and pancreatic secretion are triggered by

The correct option is B cholecystokinin
Bile juice contains bile pigments (bilirubin and biliverdin), bile salts (sodium glycocholate and sodium taurocholate), cholesterol, phospholipids. It does not contain any enzymes. It is secreted by the liver and is stored and concentrated in the gallbladder. It helps in the emulsification of fats. It also activates lipases. Cholecystokinin (pancreozymin) is secreted by the epithelium of the entire small intestine. In the pancreas, it stimulates the release of pancreatic juice. In the gallbladder, it stimulates the release of bile.
Enterogastrone (Gastric Inhibitory Peptide or GIP) is secreted by the epithelium of the duodenum. It acts on the stomach and inhibits the secretion of gastric juice. It also inhibits gastric motility. It slows down the gastric contraction.
Gastrin is secreted by the G-cells (gastrin cells) of the stomach. It is released in the pyloric region of the stomach. It acts on the gastric glands of the stomach and stimulates the secretion and release of gastric juice. It also stimulates gastric motility or the movement of chyme.
Secretin was the first hormone discovered. It is secreted by the epithelium of the duodenum. In the pancreas, it stimulates the release of bicarbonates into the pancreatic juice. In the liver, it stimulates the secretion of bile. In the stomach, it inhibits gastric secretion and motility.