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: ENT
[{'content': 'True about idiopathic sudden sensorineural loss -a) Vertigo always presentb) Carbogen ( 5% CO2 + 95 % O2) is beneficialc) Hearing loss occur within 24 hoursd) Hearing loss occur within 72 hourse) Audiometric threshold changes occur over at least 3 frequencies \nSelect and explain. \nA. bce, B. abd, C. bcde, D. acde', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]