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
Young male with painless induration of penis, enlarged non tender genital lymph nodes. Cause is - 
Select and explain. 
A. Chancroid, B. Herpes genitalis, C. Primary syphilis, D. Donovanosis
C: Primary syphilis
Answer: C: Primary syphilis 
Explanation: None