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: Social & Preventive Medicine
[{'content': 'Adjuvant used in DPT vaccine is: \nSelect and explain. \nA. Aluminium phosphate, B. Silica, C. Magnesium hydroxide, D. Manganese hydroxide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Adjuvant used in DPT vaccine is aluminium phosphate or hydroxide. Use of adjuvant increases immunological effectiveness of DPT vaccine. Ref: Park 21st edition, page 151.', 'role': 'assistant'}]