Increasing the Number of Stomata Per Unit Surface Area of a Leaf

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

A) breathing faster as atmospheric carbon dioxide levels increase
B) putting more red blood cells into circulation when oxygen availability declines at high elevations
C) breathing more slowly as atmospheric oxygen levels increase
D) increasing the volume of its lungs when atmospheric carbon dioxide levels increase