Sphincter of oddi is present at :

The correct answer is: Junction of hepato-pancreatic duct and duodenum

Explanation:
The Sphincter of Oddi (also known as the hepatopancreatic sphincter) is a muscular valve that surrounds the exit of the bile duct and pancreatic duct into the duodenum. It regulates the flow of bile and pancreatic juices into the duodenum (the first part of the small intestine) and prevents the reflux of duodenal contents back into these ducts.

Let us look at why the other options are incorrect:
1. Ileo-caecal junction: This junction contains the ileocecal valve, which controls the passage of materials from the small intestine (ileum) to the large intestine (caecum) and prevents backflow.
2. Gastro-oesophageal junction: This junction contains the gastroesophageal (or cardiac) sphincter, which controls the passage of food from the esophagus into the stomach and prevents acid reflux.
3. Junction of jejunum and duodenum: This is the duodenojejunal flexure, which is a boundary marked by the suspensory muscle of the duodenum (ligament of Treitz), not the Sphincter of Oddi.