<prompt> Answer this question truthfullyIn which zone of the lung is the VQ ratio highest?  <response>: <reason> The VQ ratio is highest in zone 1 apex of the lung. The VQ ratio, or ventilation-perfusion ratio, is a measure of the efficiency of gas exchange in the lungs. It is calculated by dividing the amount of air reaching the alveoli ventilation by the amount of blood flowing through the pulmonary capillaries perfusion. In zone 1, which is the upper part of the lung, the VQ ratio is highest because the perfusion is relatively high compared to the ventilation. This means that there is more blood flowing through the capillaries than there is air reaching the alveoli, which can lead to a decrease in carbon dioxide elimination. 