Why does it get more difficult to do a wall sit as the time passes?

Plants transfer carbon in the carbon cycle a. through assimilation of carbon from the soil. b. when carbon transpires from their stomatae. c. when they are eaten by animals. d. through fixation of carbon in the soil.plants transfer carbon in the carbon cycle a. through assimilation of carbon from the soil. b. when carbon transpires from their stomatae. c. when they are eaten by animals. d. through fixation of carbon in the soil.