In Several Studies of Plant Responses to Elevated CO₂ Concentrations

Multiple Choice

In several studies of plant responses to elevated CO₂ concentrations in the atmosphere, scientists often found that the stimulation of growth gradually diminished because

A) more photorespiration occurred.
B) C₃ plants were replaced with C₄ plants.
C) the soil did not contain sufficient nitrogen and other nutrients to support the enhanced growth.
D) the plants could not store the extra biomass.