Answer : 4. "लीज़मैनिया / लीशमैनिया"
Explanation :

1. Kala-azar disease is caused by the protozoa Leishmania donovani.

2. It is a parasitic protozoa that belongs to the class Mastigophora or Flagellata. It is caused by sand fly (Phlebotomus) which causes kala azar or dumdum fever.