This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haemophilus, Subject name: Microbiology
Causative organism of which STD has safety pin appearance- 
Select and explain. 
A. LGV, B. Chancroid, C. Syphilis, D. Herpesgenitalis
B: Chancroid
Answer: B: Chancroid 
Explanation: Ans. is 'b' i.e., Chancroid o Causative organisms of two STDs have safety pin (bipolar) appearance:i) Donovanosis or granuloma inguinale - Calymmatobacter granulomatosis.ii) Chancroid - H ducreyi