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': 'Use of a cone results in films of: \nSelect and explain. \nA. Higher contrast, B. Low contrast, C. Less motion, D. Long scale contrast', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Higher contrast', 'role': 'assistant'}]