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
Which of the following best characterizes alveolar ventilation and blood flow at the base, compared with the apex, of the lungs of a healthy standing person? 
Select and explain. 
A. Ventilation - Higher, Blood flow - Higher, V/Q ratio - Lower, B. Ventilation - Lower, Blood flow - Higher, V/Q ratio - Higher, C. Ventilation - Lower, Blood flow - Lower, V/Q ratio - Lower, D. Ventilation - Higher, Blood flow - Lower, V/Q ratio - Higher
A: Ventilation - Higher, Blood flow - Higher, V/Q ratio - Lower
Answer: A: Ventilation - Higher, Blood flow - Higher, V/Q ratio - Lower 
Explanation: Ans. A. Ventilation - Higher, Blood flow - Higher, V/Q ratio - LowerAt the base, both airflow and blood flow are higher; however, blood flow exceeds airflow at the base, which results in a low V.A/Q. ratio. At the apex, blood flow and airflow are lower than at the base, but airflow is greater than blood flow, which leads to a high V.A/Q..