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': 'Frozen DPT vaccine should be - \nSelect and explain. \nA. Shaken thoroughly before use, B. Allowed to melt before use, C. Discarded, D. Brought to room temperature before use', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]