This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Preoperative assessment and monitoring in anaesthesia, Subject name: Anaesthesia
During a pre-anaesthetic evaluation of a patient with neck extended, mouth open, and tongue protruded, the patient's uvula is not visible. His airway should be classified as which of the following 
Select and explain. 
A. Mallampati 1, B. Mallampati 2, C. Mallampati 3, D. None of the above
C: Mallampati 3
Answer: C: Mallampati 3 
Explanation: Since this patient's uvula is not visible, his airway is classed as Mallampati 3, suggesting a difficult intubation.