This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Medicine
[{'content': 'Initial investigation done in obstructive jaundice is? \nSelect and explain. \nA. ERCP, B. Ultrasound, C. Cholecystography, D. MRCP', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Diagnostic Advantages of Hepatobiliary Ultrasound Hepatobiliary Diagnostic Limitations of Ultrasound Remarks Rapid evaluation of liver and bile ducts Accurate identification of dilated bile ducts Not limited by pregnancy Guidance for fine-needle Biopsy Bowel gas Ascites Poor visualisation of distal C.B.D Initial Procedure of choice in biliary tract obstruction', 'role': 'assistant'}]