Refer to the Graph

question 100

Multiple Choice

Refer to the graph. The FACE experiment conducted in a North Carolina pine forest analyzed the effects of two factors on forest NPP.These two factors were

• A) low and high levels of CO₂.
• B) low and high levels of nitrogen fertilization.
• C) levels of CO₂ and nitrogen fertilization.
• D) levels of CO₂ and atmospheric temperature.
• E) levels of nitrogen and atmospheric temperature.