This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'Normal voice heard from 1 meter, intensity of sound reaching ear is - \nSelect and explain. \nA. 20 dB, B. 40 dB, C. 60 dB, D. 80 dB', 'role': 'user'}, {'content': "Answer: C \nExplanation: Normal conversation produces 60-70 dB. Whisper 20-30 dB. Mechanical damage at 150-160 dB REF. PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICINE 22nd EDITION. PAGE NO - 688", 'role': 'assistant'}]