This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 1, Subject name: Forensic Medicine
Brain is preserved in all of the following, except: 
Select and explain. 
A. OPC poisoning, B. Alkaloid poisoning, C. Heavy metal poisoning, D. Volatile organic poisoning
C: Heavy metal poisoning
Answer: C: Heavy metal poisoning 
Explanation: Preservation of additional viscera: (1) Hea: strychnine, digitalis, yellow oleander. (2) Brain: alkaloids, OPC , opiates, CO, cyanide, strychnine, barbiturates; and volatile organic poisons. (3) Spinal cord: strychnine and gelsemium. (4) C.S.F: alcohol (5) Bile: Narcotic drugs, cocaine, methadone, glutathione, barbiturates (6) Vitreous humour: alcohol, chloroform, cocaine. (7) Lung: one lung in gaseous poisons, hydrocyanic acid, alcohol, chloroform, etc. (8) Bone: arsenic, antimony, thallium or radium. (9) Fat: 10 gm from abdominal wall or perinephric region in cases of poisoning by pesticides and insecticides.