<prompt> True statement regarding pulmonary ventilation is -PaO2 is maximum at the apexVQ is maximum at the baseVentilation per unit lung volume is maximum at the apexBlood circulation is minimum at the base  <response>: Apical alveoli have low ventilation and perfusion per unit volume of the lung, whereas the basal alveoli have high ventilation and perfusion.Ventilation-perfusion ratio and the PaO2 is maximum at the apex. PCO2 is maximum at the base. 