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
With optical density of 2, percentage of light transmitted is: 
Select and explain. 
A. 100%, B. 10%, C. 1%, D. 0.10%
C: 1%
Answer: C: 1% 
Explanation: The degree of darkening or opacity of an exposed film is referred to as optical density. The optical density of an area of an X-ray film can be measured as follows: