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: Radiology
[{'content': 'Which is not required for visualisation of gallbladder in oral cholecystography – \nSelect and explain. \nA. Functioning liver, B. Motor mechanisms of gall bladder, C. Patency of cystic duct, D. Ability to absorb water', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Visualization of the gallbladder in OCG depends on:-\n\nIngestion of dye\nAbsorption of dye in gut\nBlood flow to liver (Entero-hepatic-circulation)\nTake up in liver (functional liver), ability of liver to excrete dye into the bile (functional liver)\nThe ability of gallbladder to concentrate the excreted dye (by absorbing water)\nPatency of hepatic & cystic duct system', 'role': 'assistant'}]