Increasing the number of stomata per unit surface area of a leaf when atmospheric CO₂ levels decline is most analogous to a human

A)breathing faster as atmospheric CO₂ levels increase.
B)putting more red blood corpuscles (RBCs)into circulation when atmospheric O₂ levels decline.
C)removing RBCs from circulation when atmospheric O₂ levels increase.
D)breathing more slowly as atmospheric O₂ levels increase.