Final answer:
The duodenum is the first segment of the small intestine with a primary function of chemical digestion.Thus, the correct answer to the question is a) Duodenum.
Step-by-step explanation:
The duodenum is the first segment of the small intestine. Compared to the other parts, it is the shortest segment, averaging about 25 cm (10 inches) in an adult, and it serves a crucial role in the digestive system. The duodenum's main function is chemical digestion, where most chemical digestion takes place due to the secretion of digestive juices that contain enzymes to break down complex food molecules. Following the duodenum is the jejunum, which is responsible for the majority of nutrient absorption, and the ileum is the final and longest section of the small intestine, where the remaining nutrient absorption occurs, especially that of vitamin B12 and bile salts. Thus, the correct answer to the question is a) Duodenum.
The first segment of the small intestine is called the duodenum. It is the shortest part of the small intestine and is directly connected to the stomach. The duodenum is where most chemical digestion takes place.