This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: X-RAYS, Subject name: Radiology
[{'content': 'SAFE LIGHT used in conventional radiography emits which colour of light? \nSelect and explain. \nA. Blue, B. Green, C. Red, D. Yellow', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Darkrooms used red lighting to allow radiographers to control light carefully, so that light-sensitive photographic film would not become overexposed and ruin the image quality during the developing process.', 'role': 'assistant'}]