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
Tetany is caused by which poisoning : 
Select and explain. 
A. Oxalic acid, B. Carbolic acid, C. Sulphuric acid, D. Nitric acid
A: Oxalic acid
Answer: A: Oxalic acid 
Explanation: Oxalic acid combines with calcium and causes its withdrawal from them causing hypocalcemia.
In acute poisoning by oxalic acid, it produces hypocalcemia leading to muscle irritability, tetany & convulsions.