This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
Blood cholinesterase level should be estimated for three weeks, in non-fatal cases of poisoning with- 
Select and explain. 
A. Parathion, B. Eldrine, C. Thallium sulphate, D. Arsenic oxide
A: Parathion
Answer: A: Parathion 
Explanation: Parathion is an organophosphorus compound (plasma cholinesterase activity is measured in poisoning of organophosphorus compounds).