This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
The release of which one of the following into ponds and wells helps in controlling the mosquitoes? 
Select and explain. 
A. Crab, B. Dogfish, C. Gambusia fish, D. Snail
C: Gambusia fish
Answer: C: Gambusia fish 
Explanation: Biological control of mosquito larva include growing larvivorous fishes in the burrow pits,oxidation ponds,ornamental ponds .Theya re Gambusia affinis and Lebister reticulatus. Other antilarval measures are source reduction ,filling ,intermitent irrigation.chemical control by using mineral oils and paris green. Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: :772