**Core Concept**
Cholecystokinin (CCK) is a gastrointestinal hormone that plays a crucial role in regulating digestion. It is released by the duodenum in response to the presence of fat and protein in the small intestine and acts to stimulate the release of digestive enzymes and bile from the pancreas and gallbladder, respectively.

**Why the Correct Answer is Right**
CCK exerts its effects through binding to CCK receptors on the surface of pancreatic acinar cells, gallbladder smooth muscle, and other target tissues. This binding triggers a series of downstream signaling events that ultimately lead to the release of digestive enzymes and bile into the small intestine. Additionally, CCK also stimulates the contraction of the gallbladder to release bile into the bile duct.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because CCK does indeed stimulate the contraction of the gallbladder, which is essential for the release of bile into the bile duct. This action is a key component of the digestive process.

**Option B:** This option is incorrect because CCK does stimulate the release of digestive enzymes from the pancreas, including amylase, lipase, and trypsin. These enzymes are essential for the breakdown of carbohydrates, fats, and proteins, respectively.

**Option C:** This option is incorrect because CCK does stimulate the release of bile from the gallbladder, which is essential for the emulsification and absorption of fats in the small intestine.

**Clinical Pearl / High-Yield Fact**
It is worth noting that CCK also has a role in regulating appetite and satiety, with administration of CCK analogs being used as a potential treatment for obesity.

**Correct Answer: D.**