Correct option is (A)
The human sphincter of Oddi. ... The sphincter of Oddi (SO) is critically located at the junction of the common bile duct (CBD), main pancreatic duct, and the duodenum. It is a high-pressure zone with phasic contractions that regulate bile and pancreatic juice flow.

The Sphincter of Oddi is situated in the Ampulla of Vater.

The Sphincter of Oddi is a muscular valve located at the junction of the common bile duct and the pancreatic duct. It controls the flow of bile and pancreatic juice into the duodenum, the first part of the small intestine.

Function of the Sphincter of Oddi:
The main function of the Sphincter of Oddi is to regulate the flow of bile and pancreatic juice into the duodenum. It opens and closes in response to various stimuli to ensure the proper release of these digestive fluids.

Location of the Ampulla of Vater:
The Ampulla of Vater, also known as the hepatopancreatic ampulla or the hepatopancreatic duct, is a small enlargement located at the junction of the common bile duct and the pancreatic duct. It is situated in the second part of the duodenum, just before it enters the jejunum, which is the next segment of the small intestine.

Role of the Ampulla of Vater:
The Ampulla of Vater acts as a meeting point for the common bile duct and the pancreatic duct. It serves as a storage area for bile and pancreatic enzymes, allowing them to mix and be released into the duodenum when needed for digestion. The Sphincter of Oddi, located within the ampulla, controls the opening and closing of this junction to regulate the flow of bile and pancreatic juice.

Significance of the Sphincter of Oddi:
The Sphincter of Oddi plays a crucial role in preventing the reflux of bile and pancreatic juice back into the common bile duct and pancreatic duct. It ensures that these digestive fluids are released into the duodenum at the appropriate time, facilitating the digestion and absorption of nutrients in the small intestine.

In summary:
The Sphincter of Oddi is situated in the Ampulla of Vater, which is located at the junction of the common bile duct and the pancreatic duct. This sphincter regulates the flow of bile and pancreatic juice into the duodenum, ensuring proper digestion and absorption of nutrients.

The correct word should be 'the common hepato-pancreatic duct'.