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. Filariasis:$\newline$ - Filariasis is a parasitic disease caused by thread-like filarial worms.$\newline$ - The most common causative agent is Wuchereria bancrofti.$\newline$ - This matches with iii.$\newline \bullet$b. Amoebiasis:$\newline$ - Amoebiasis is an intestinal illness caused by the protozoan parasite Entamoeba histolytica.$\newline$ - This matches with iv.$\newline \bullet$c. Pneumonia:$\newline$ - Pneumonia is an infection that inflames the air sacs in one or both lungs.$\newline$ - A common bacterial cause is Haemophilus influenzae.$\newline$ - This matches with i.$\newline \bullet$d. Ringworm:$\newline$ - Ringworm is a fungal infection of the skin.$\newline$ - It is commonly caused by fungi of the genus Trichophyton.$\newline$ - This matches with ii.$\newline$Now, let's match the items from List I with List II:$\newline a \rightarrow iii, b \rightarrow iv, c \rightarrow i, d \rightarrow ii \newline$This corresponds to Option 2.