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
Following is a contact poison - 
Select and explain. 
A. BHC, B. BaSO4, C. A + B of above, D. Paris green
A: BHC
Answer: A: BHC 
Explanation: Insecticides are substances used to kill insects.They are 3 gruops: contact poison,stomach poison,fumigants. Contact poisons- BHC,DDT,lindanediazinon,malathion,fenthion. Stomach paoisons are paris green and sodium flouride . Fumigants are hydrogencyanide,methyl bromide,sulpher dioxide. Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 783