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
How should the lingual extension of the mandibular impression be tested 
Select and explain. 
A. By functional movements of the facial muscles, B. By vigorous extreme movements of the tongue, C. By functional movements of the tongue, D. By lateral and protrusive movement of the mandible
C: By functional movements of the tongue
Answer: C: By functional movements of the tongue 
Explanation: None