This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
Audiogram in early Meniere's disease shows: 
Select and explain. 
A. Notch at 2 kHz in bone conduction, B. Notch at 4 kHz in air conduction, C. A flat curve, D. A rising curve
D: A rising curve
Answer: D: A rising curve 
Explanation: In early cases of Meniere's disease low frequencies are affected more and the audiogram shows a rising curve. In long-standing cases, audiogram becomes fiat and then falling type.Notch at 2 kHz in bone conduction is typically seen in Carhart's notch seen in otosclerosis (5 dB at 500 Hz, 10 dB at 1000 Hz, 15 dB at 2000 and 5 dB at 4000 Hz).Notch at 4 kHz both in air and bone conduction is seen in noise-induced hearing loss. As the duration of noise exposure increases, notch at 4 kHz deepens and widens to involve other frequencies.