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': 'The impression for a diagnostic cast of a partial edentulous mouth should be taken in: \nSelect and explain. \nA. Impression wax, B. Modelling compound, C. Hydro-colloid, D. Hydro cal', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]