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: Medicine
[{'content': 'Kussmaul’s sign is classically seen in \nSelect and explain. \nA. Infective endocarditis, B. Malignant hypertension, C. Constrictive pericarditis, D. Patent ductus arteriosus', 'role': 'user'}, {'content': "Answer: C \nExplanation: Normally,\xa0the venous pressure should fall by at least 3 mmHg with inspiration. Kussmaul's sign is defined by either a rise or a lack of fall of the JVP with inspiration and is classically associated with constrictive pericarditis,\xa0although it has been reported in patients with restrictive cardiomyopathy,\xa0massive pulmonary embolism, right ventricular infarction and advanced left ventricular systolic heart failure.", 'role': 'assistant'}]