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: Physiology
Low calcium level will cause: 
Select and explain. 
A. Hyper excitability of wrist muscle, B. Weak heart action, C. Tetany, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None