Final answer:
The most of the Main Pancreatic Duct comes from the head of the pancreas, which also produces the majority of fat-digesting enzymes through its acinar cells.
Step-by-step explanation:
The portion of the Pancreas from which most of the Main Pancreatic Duct comes from is the head of the pancreas. This duct is part of the exocrine function of the pancreas, where exocrine cells secrete enzyme-rich pancreatic juice. The main pancreatic duct fuses with the common bile duct and enters the duodenum at the hepatopancreatic ampulla. Meanwhile, most fat-digesting enzymes are produced in the pancreas, more specifically by its acinar cells, which secrete this juice into the merging ducts leading to the main pancreatic duct.