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 measures the vertical dimension when the mandible and muscles involved are in physiologic function of speech? 
Select and explain. 
A. Free way space, B. Leeway space, C. Closest speaking space, D. Primate space
C: Closest speaking space
Answer: C: Closest speaking space 
Explanation: None