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: Social & Preventive Medicine
Thickness offend apron to prevent radiation? 
Select and explain. 
A. 1 mm, B. 3 mm, C. 0.5mm, D. 7mm
C: 0.5mm
Answer: C: 0.5mm 
Explanation: Ans. is 'c' i.e., 0.5 mm o Lead aprons (0.5 mm of lead) will reduce the intensity of scattered X-ray over 90% and should be worn by all workers regularly associated with x-ray procedures.