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
Which of the following statements is true regarding digital clubbing? 
Select and explain. 
A. 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
B: Clubbing is seen in pulmonary arteriovenous fistula
Answer: B: Clubbing is seen in pulmonary arteriovenous fistula 
Explanation: None