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: Radiology
Which element of the following on disintegration leads to daughter element in gaseous form? 
Select and explain. 
A. Radium, B. Iridium, C. Radon, D. Uranium
A: Radium
Answer: A: Radium 
Explanation: As radium decays or disintegrates, it forms Radon gas (earth’s only naturally produced radioactive gas),
which can enter homes, buildings, and wells and if not ventilated may cause Radiation sickness.