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: Pathology
Which	of	the	following	is	associated	with	a	low
concentration of ionized calcium in the serum? 
Select and explain. 
A. Hypothyroidism, B. Osteogenesis imperfecta, C. Paget's disease of the bone, D. Tetany
D: Tetany
Answer: D: Tetany 
Explanation: None