Final answer:
Fat digestion mainly occurs in the small intestine, where pancreatic lipase breaks down fats into absorbable molecules, aided by bile which emulsifies fats into micelles.
Step-by-step explanation:
Almost all fat digestion occurs in the small intestine due to the action of pancreatic lipase. Pancreatic lipase is crucial because it breaks down each triglyceride into two free fatty acids and a monoglyceride. These molecules are then absorbed through the intestinal lining into the bloodstream. Although bile, produced by the liver and stored in the gallbladder, doesn't directly digest fats, it emulsifies them into micelles, increasing the surface area for pancreatic lipase to act upon. The substances formed after fat digestion, chylomicrons, are large spheres that transport fats through the lymphatic system and into the bloodstream. Therefore, the correct answer is 'a) Pancreatic lipase'.