Final answer:
The correct order of the small intestine from first to last part is duodenum, jejunum, and ileum, with each part carrying out different functions in digestion and absorption.
Step-by-step explanation:
The correct order of the parts of the small intestine, starting with the first part, is duodenum, jejunum, ileum. The duodenum is the first section where most chemical digestion takes place. Following the duodenum is the jejunum, which is the second part of the small intestine responsible for most nutrient absorption. Lastly, the ileum is the final section, which is the longest part of the small intestine and is responsible for the absorption of bile salts and certain vitamins.