When Plants Are Initially Exposed to Elevated Carbon Dioxide Levels

When plants are initially exposed to elevated carbon dioxide levels most increase their rate of photosynthesis; how might plant communities be affected?

A) no changes other than increased NPP
B) competition increases for other resources such as sunlight or phosphorus with the eventual disappearance of some community members
C) community members decrease in size over time with the removal of the selection pressure for carbon dioxide acquisition
D) Since carbon dioxide is never a limiting factor like water, nitrogen, or phosphorus, increased levels typically have no significant effects.