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: ENT
Laryngeal mirror is warmed before use by placing - 
Select and explain. 
A. Glass surface on flame, B. Back of mirror on flame, C. Whole mirror into flame, D. Mirror in boiling water
A: Glass surface on flame
Answer: A: Glass surface on flame 
Explanation: Laryngeal mirror is warmed by: 

Dipping the mirror in warm water.
Heating the glass surface against some heat such as bulb or spirit lamp.