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: Surgery
Painless ulcer of the tongue is due to : 
Select and explain. 
A. Dyspepsia, B. Syphilis, C. Tuberculosis, D. None of the above
B: Syphilis
Answer: B: Syphilis 
Explanation: Syphilis chancres can occur in the mouth and they are painless.