This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cystic fibrosis & Sleep apnea, Subject name: Medicine
Which is not true of obstructive sleep apnea? 
Select and explain. 
A. Nocturnal asphyxia, B. Alcoholism is a cofactor, C. Prone to hypeension, D. Spirometry is diagnostic
D: Spirometry is diagnostic
Answer: D: Spirometry is diagnostic 
Explanation: An overnight sleep study, or polysomnography, is required to diagnose OSA. PSG: in-laboratory measurement of sleep architecture and EEG arousals, eye movements, oximetry, snoring, and leg movements OSAHS raises 24-h mean blood pressure.