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: Dental
[{'content': 'For locating clasp patterns, which block out is used? \nSelect and explain. \nA. Parallel block out, B. Shaped block out, C. Arbitrary block out, D. Relief', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]