This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Physiology of Hearing, Subject name: ENT
Patient presents with severe hearing loss. For the amount of decibel loss he has, which of the following sound can be heard by him? 
Select and explain. 
A. Rustling of leaves, B. Sta of car engine at 10 feet, C. Sound of Niagara falls, D. Noisy environment night street
C: Sound of Niagara falls
Answer: C: Sound of Niagara falls 
Explanation: WHO CLASSIFICATION Till 25 dB Hz Normal 26 - 40 dB Hz Mild 41 - 60 dB Hz Moderate 61 - 80 dB Hz Severe Over 81 dB Profound Source Decibels Anything on the verge of being Audible 0 Whisper 30 Normal conversation 60 Busy traffic 70 Niagara Falls 90 Train 100 Construction noise 110 Rock conce 120 Machine gun 130 Jet take off 150 Rocket take off 180