Cholecystokinin causes:

Cholecystokinin (CCK) is a hormone produced by the small intestine in response to the presence of fats and proteins in the digestive tract. One of its primary actions is to stimulate the contraction of the gallbladder. This results in the release of bile into the small intestine, which is essential for the digestion and emulsification of fats.

The stimulation of gallbladder contraction is a critical component of the digestive process, as it helps ensure that the bile is available in the duodenum when fatty foods are consumed. This action is particularly important for the efficient digestion and absorption of lipids.

While CCK does have other roles, such as promoting pancreatic enzyme secretion and moderating gastric emptying, its most direct effect is on the gallbladder itself, making contraction of the gallbladder the most accurate response to the question.