Final answer:
The duodenum is the first part of the small intestine and extends from the stomach to the small intestine, where chemical digestion occurs(opton d).
Step-by-step explanation:
The duodenum is the first segment of the small intestine, immediately following the stomach. It is distinguished by being the shortest section within the small intestine and it starts at the pyloric sphincter. The descending portion of the duodenum extends from the stomach to the small intestine, and this section is integral in the process of chemical digestion. Here, the chyme from the stomach mixes with digestive juices from the pancreas, liver, and gallbladder, as well as enzymes produced by the duodenum's walls.
The function of the duodenum includes the neutralization of stomach acids through bicarbonate-rich pancreatic juices, emulsification of fats by bile salts, and the breakdown of proteins, fats, and carbohydrates. This allows for their subsequent absorption in later sections of the small intestine.
The correct answer to the question is D) Extending from the stomach to the small intestine.