**Core Concept**
The main pancreatic duct is a vital anatomical structure that plays a crucial role in the exocrine function of the pancreas. It is a duct that carries pancreatic juice, which is rich in digestive enzymes, from the pancreas to the small intestine. The development of the main pancreatic duct is closely linked to the embryological development of the pancreas.

**Why the Correct Answer is Right**
The main pancreatic duct is primarily derived from the duct of Wirsung, which is one of the two main pancreatic ducts in the pancreas. The duct of Wirsung is a larger and more prominent duct that runs along the posterior aspect of the pancreas and opens into the second part of the duodenum. The duct of Wirsung is responsible for carrying the majority of the pancreatic juice from the pancreas to the small intestine. In contrast, the duct of Santorini is a smaller duct that opens into the second part of the duodenum and is responsible for carrying a smaller amount of pancreatic juice.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the duct of Santorini is not the primary source of the main pancreatic duct.
**Option B:** This option is incorrect because the ampulla of Vater is the opening of the main pancreatic duct into the second part of the duodenum, not the source of the main pancreatic duct itself.
**Option C:** This option is incorrect because the accessory pancreatic duct, also known as the duct of Santorini, is a smaller duct that opens into the second part of the duodenum and is not the primary source of the main pancreatic duct.

**Clinical Pearl / High-Yield Fact**
The main pancreatic duct is a critical anatomical structure that is often involved in pancreatic diseases such as pancreatitis and pancreatic cancer. Knowledge of the embryological development of the pancreas and the anatomy of the main pancreatic duct is essential for understanding these diseases.

**Correct Answer: C. Duct of Wirsung.**