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: Surgery
The best monitor of the level of analgesia is: 
Select and explain. 
A. Verbal response., B. Touch response., C. Optic response., D. All of the above.
A: Verbal response.
Answer: A: Verbal response. 
Explanation: Verbal response is the best monitor to check the level of analgesia.