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: Microbiology
Vector for Kala-azar - 
Select and explain. 
A. Flea, B. Tsetse fly, C. Sand fly, D. Tick
C: Sand fly
Answer: C: Sand fly 
Explanation: Sandflies of genera Phlebotomus act as intermediate host for Leishmaniasis (Kala-azar).
Human and other vertebrates act as definitive host.