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': 'Agar is prepared from: \nSelect and explain. \nA. Bullock heart, B. Chemicals, C. Seaweed, D. Chick cells', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Agar, a polysaccharide extracted from certain types of seaweed, is the main active ingredient in the material, while water is the major constituent in the agar impression material.\nReference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 170', 'role': 'assistant'}]