This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Medical, surgical and gynaecological illness complicating pregnancy, Subject name: Gynaecology & Obstetrics
[{'content': 'Best diagnostic test for cholestasis of pregnancy: \nSelect and explain. \nA. Serum bilirubin, B. Bile acid, C. Serum alkaline phosphatase, D. Serum transaminase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Liver function tests, including serum bile acids are Evaluated. Bile acids are the specific measure of the diagnosis and monitoring. Liver USG is to be done to exclude cholelithiasis. Reference: Textbook of Duttas, 9th edition ,page 271', 'role': 'assistant'}]