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: Microbiology
[{'content': 'Cold sterilization is ? \nSelect and explain. \nA. Ionizing radiation, B. Mechanical filtration, C. Ultrasonic, D. Sonic vibrations, heating, then sudden cooling', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Ionizing radiation", 'role': 'assistant'}]