To solve this problem, we need to match the diseases in List I with their corresponding causative agents in List II. Let's analyze each disease:$\newline \bullet$A. Typhoid:$\newline$Typhoid is caused by the bacterium $\textit{Salmonella typhi}. \newline$This matches with IV. Bacteria.$\newline \bullet$B. Leishmaniasis:$\newline$Leishmaniasis is caused by protozoan parasites belonging to the genus $\textit{Leishmania}. \newline$