The scientific name of the causal organism of elephantiasis is Wuchereria bancrofti, which is the correct answer in this case. Let`s examine the other options to better understand why they are not the correct answers.
Option 1: Ascaris lumbricoides is the scientific name for the roundworm that causes ascariasis, a different parasitic infection. Ascariasis primarily affects the intestines and does not cause elephantiasis.
Option 2: Culex pipiens is a species of mosquito and is not the causal organism of elephantiasis. Mosquitoes are vectors for transmitting diseases like malaria and dengue fever, but not elephantiasis.
Option 4: Fasciola hepatica is the scientific name for the liver fluke, a parasite that primarily affects the liver and bile ducts. It is not associated with elephantiasis.
Therefore, the correct answer remains option 3, Wuchereria bancrofti, which is the scientific name of the causal organism responsible for elephantiasis.