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
Soft sore is caused by? 
Select and explain. 
A. H ducreyi, B. Calymmatobacteriumgranulomatis, C. Chlamydia trachomitis, D. T. Pallidum
A: H ducreyi
Answer: A: H ducreyi 
Explanation: Ans. is "a' i.e., H ducrevi o Lesion of primary syphilis-Chancre (Hard - chancre).o Lesion of H. Ducreyi-Chancroid (Soft - chancre).