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: Pathology
Du Bois sign seen in syphilis is: 
Select and explain. 
A. Shortening of the little finger, B. Small patches are seen on the back, C. Tightening of the fingers, D. All of the above
A: Shortening of the little finger
Answer: A: Shortening of the little finger 
Explanation: According to the current literature, the term "du Bois sign" characterizes the condition of a shortened fifth finger as a symptom of congenital syphilis.