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
Freeway space is defined as: 
Select and explain. 
A. Vertical dimension at rest - vertical dimension at occlusion, B. Vertical dimension at occlusion + vertical dimension at rest, C. Vertical dimension at rest, D. Vertical dimension at occlusion - vertical dimension at rest
A: Vertical dimension at rest - vertical dimension at occlusion
Answer: A: Vertical dimension at rest - vertical dimension at occlusion 
Explanation: None