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': 'Which of the following statements is true regarding digital clubbing? \nSelect and explain. \nA. Clubbing always indicates heart disease, B. Clubbing is seen in pulmonary arteriovenous fistula, C. Clubbing is common in cirrhosis of the liver, D. Presence of clubbing warrants a search for sickle cell disease', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]