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
A pinch of which of the following poisons can kill as many as five persons : 
Select and explain. 
A. Arsenic trioxide, B. Copper sulphate, C. Lead sulphate, D. Arsenic disulphate
A: Arsenic trioxide
Answer: A: Arsenic trioxide 
Explanation: A i.e. Arsenic trioxide