In the following diagram, the curve "X" represents the normal relationship of alveolar ventilation with PaCO2 when PaO2 is 100 mmHg. If pH changed from 7.4 to 7.3, change in alveolar ventilation will shift to which of the curve?

This graph shows the composite effects of PCO2, pH , PO2 on alveolar ventilation Red curves are measured at blood pH of 7.4 Green curves are measured at blood pH of 7.3 Curves are displaced to right at higher ph & displaced to left at lower pH Ref: Guyton, 13th edition / page 544