This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Micelles are formed by: \nSelect and explain. \nA. Triacylglycerol in polar solvent, B. Amphipathic lipids in water, C. Triacylglycerol in gut, D. Cholesterol esters', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Bile salts, when in high enough concentration in water, have the propensity to form micelles, which are small spherical, cylindrical globules 3 to 6 nanometers in\xa0 diameter composed of 20 to 40 molecules of bile salt. These develop\xa0because each bile salt molecule is composed of a sterol nucleus that is highly fat-soluble and a polar group that is highly water-soluble. The sterol nucleus encompasses the fat digestate, forming a small fat globule in the middle of\xa0a resulting micelle, with polar groups of bile salts projecting outward to cover the surface of the micelle. Because these polar groups are negatively charged, they allow the entire micelle globule to dissolve in the water of the digestive fluids and to remain in stable solution until the fat is absorbed into the blood.', 'role': 'assistant'}]