This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Physiology
Ventilation-perfusion ratio is least at 
Select and explain. 
A. Apex, B. Middle lob, C. Base, D. None
C: Base
Answer: C: Base 
Explanation: In respiratory physiology, the ventilation/perfusion ratio (V/Q ratio or V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching of two variables: V or V - ventilation - the air that reaches the alveoli. Q or Q - perfusion - the blood that reaches the alveoli the capillaries Ref: guyton and hall textbook of medical physiology 12 edition page number:331,332,333