This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: S.T.D., Subject name: Skin
A sexually active male comes with multiple painful ulcers, the smear is enclosed? What is the most likely diagnosis? 
Select and explain. 
A. Chancre, B. Chancroid, C. Herpes, D. Aphthosis
B: Chancroid
Answer: B: Chancroid 
Explanation: Ans. B. ChancroidImage shows pleomorphic gram negative coccobacilli (H. ducreyi) arranged in a parallel chains of two's or four described as "School of fish"