This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: COPD and Asthma, Subject name: Medicine
The following are indications for assisted ventilation in acute severe asthma EXCEPT? 
Select and explain. 
A. PEFR 50-60% of predicted value, B. Rising PaCO2> 6kPa (45 mm Hg), C. Diminishing level of consciousness, D. Falling PaO2< 8kPa (60 mm Hg)
A: PEFR 50-60% of predicted value
Answer: A: PEFR 50-60% of predicted value 
Explanation: PEFR of 50-60% indicates moderate asthma. Indication for intubation in asthma exacerbation is a poor response to oxygen with salbutamol nebulisation and oral steroids. The definition of poor response is: 1. FEV1< 40%. 2. PaCO2> 45mmHg. 3. Features of carbon dioxide narcosis. 4. Hypoxia defined as PaO2<60 mm Hg.