## **Core Concept**
Cholecystokinin (CCK) is a peptide hormone of the gastrointestinal (GI) tract that plays a crucial role in digestion. It is released by the duodenum in response to a meal, especially one rich in fat and protein. CCK acts on various targets to facilitate digestive processes.

## **Why the Correct Answer is Right**
The correct answer, which involves the contraction of the gallbladder, relaxation of the sphincter of Oddi, and stimulation of pancreatic enzyme secretion, is right because CCK causes:
- **Gallbladder contraction**: CCK stimulates the gallbladder to contract, releasing bile into the bile duct and then into the small intestine to emulsify fats.
- **Relaxation of the sphincter of Oddi**: This allows bile and pancreatic juices to flow into the intestine.
- **Stimulation of pancreatic enzyme secretion**: CCK stimulates the pancreas to secrete digestive enzymes into the duodenum to facilitate the digestion of proteins, carbohydrates, and fats.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because CCK does not primarily cause an increase in gastric emptying; in fact, it can slow gastric emptying to allow for more efficient digestion in the small intestine.
- **Option B:** This option is incorrect as CCK does not primarily stimulate the secretion of gastric acid; that is more the role of gastrin.
- **Option D:** This option is incorrect because while CCK does have some effect on gut motility, its primary actions are on the gallbladder, pancreas, and sphincter of Oddi.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that CCK is released in response to food, particularly fat and protein, and it plays a pivotal role in facilitating the digestion and absorption of nutrients. This hormone's actions are critical for the proper functioning of the digestive system, especially in the postprandial state.

## **Correct Answer:** C. Contraction of gall bladder, relaxation of sphincter of oddi and stimulation of pancreatic enzyme secretion.