Which of the following is a Nematode responsible for Elephantiasis disease?

Nematodes are commonly known as roundworms. They live as parasites in animals and plants and cause many diseases.
Wuchereria is a roundworm that causes elephantiasis in humans. It is characterized by swollen limbs and genitals in the affected person. The larvae of the roundworm clog the lymph nodes causing retention of fluid in the tissues. 

Since the affected organ is mostly the leg which swells immensely and appears like a leg of an elephant, the disease is called elephantiasis.