The hormone which brings about the contraction of gall bladder is

The correct option is C Cholecystokinin

A. Oxytocin is secreted from the posterior pituitary and helps in the contraction of uterus during childbirth and also stimulates release of milk from mammary glands i.e. lactation.

B. Gastrin is secreted in stomach by the parietal cells and stimulates the secretion of gastric juices from the gastric glands.

C. Cholecystokinin is secreted from the duodenum and causes contraction of gall bladder and secretion of pancreatic juice into duodenum.

D. Secretin is secreted in duodenum and stimulates the secretion of pancreatic juice but inhibits the secretion of gastric juices.

So, the correct answer is 'Cholecystokinin'.