This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parasitology, Subject name: Microbiology
River blindness is caused by: 
Select and explain. 
A. Onchocerca, B. Loa Loa, C. Ascaris, D. B. malayi
A: Onchocerca
Answer: A: Onchocerca 
Explanation: Ans. is 'a' i.e., Onchocerca(Ref: Harrison, 19th/e, p. 1421)* Onchocerciasis is also known as River blindness Q and fly involved is Simulium fly.