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
[{'content': 'With optical density of 2, percentage of light transmitted is: \nSelect and explain. \nA. 100%, B. 10%, C. 1%, D. 0.10%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 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:', 'role': 'assistant'}]