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': 'A young female presents with chest pain not associated with exercise. Auscultation reveals multiple ejection clicks with a murmur. The most impoant investigation for diagnosis is: \nSelect and explain. \nA. ECG, B. Thallium 201 scan, C. Tc pyrophosphate scan, D. Echocardiography', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Echocardiography', 'role': 'assistant'}]