Final answer:
The peritoneum is not a part of the pancreas, which consists of the head, body, and tail. The peritoneum is a lining for the abdominal cavity.
Step-by-step explanation:
The pancreas is a glandular organ with both endocrine and exocrine functions, located in the abdomen behind the stomach. Its main parts include the head, which is nestled into the curvature of the duodenum, the body extending towards the left, and the tail that tapers off near the spleen. These parts are integral to its role in secreting digestive enzymes and hormones like insulin and glucagon into the bloodstream. However, the peritoneum is not a part of the pancreas; rather, it is a membrane that lines the abdominal cavity and covers abdominal organs. Thus, in the provided question, the correct answer is 'a. peritoneum', as it is not a part of the pancreas.