The correct option is B Gangrene
Gangrene is caused by blocked blood flow or by a bacterial infection which causes the death of the living organism. It mostly affects the legs, feet, arms, and fingers, but it also can affect internal organs such as the intestine or gallbladder. It is spread by maggots, larvae of houseflies. Dengue fever, encephalitis, and filariasis are transmitted by mosquitoes. So, the correct answer is option D.