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: Dental
Which of the following is false about conscious sedation? 
Select and explain. 
A. Patient retains ability to maintain a patent airway, B. Responds appropriately to physical stimulation, C. Responds appropriately to verbal commands, D. None of the above
D: None of the above
Answer: D: None of the above 
Explanation: None