Wuchereria bancrofti is transmitted by.
A. Tsetse fly
B. Anopheles mosquito
C. Culex mosquito
D. Sand fly

Hint: This organism is from the filaria family and its different species are known to cause filariasis in humans as reported. This organism cannot directly affect the human and instead it requires a vector to enter its host. It is generally spread by the biting of a specific organism present around humans in abundance.

Complete answer:
Filariasis, is the disease caused by the above-mentioned organism which is Wuchereria bancrofti. This organism is known to cause infection only in its adult stage and the juvenile stages are not reported to cause any disease in the humans. If we discuss the organs affected by these organisms then they are the lymph nodes comprising the lymphatic system of the body.
Now considering the life cycle of these organisms we will observe that they need a primary host in which their development is taking place. They also require a primary host in order to move into the secondary host where they are known to cause infection. The primary host is also known as the vector of the disease. The transfer of the adults from the primary host is done by their biting and the filaria gets transferred to the secondary hosts. These organisms are present in the salivary glands of the insect.
Now we know how the disease is spreading and where it is situated in the vector. So, from our discussion and the options given we can say that the option A and D are incorrect because flies do not bite humans but the mosquito species is known to bite humans and cause a variety of diseases.

The anopheles’ mosquito is known to cause malaria disease and this leaves us with the option C which is the correct answer.

Note:
The filaria get transmitted to humans via the biting and it enters the bloodstream and with the flow of blood steam it reaches the lymph nodes where it is known to cause much damage. When a mosquito bites a human again then this organism gets into the mosquito and the cycle repeats.