Which of These Best Describes the Comparison of Observed Changes

Which of these best describes the comparison of observed changes in CO₂ production and IPCC model scenarios of expected CO₂ production?

A) Model scenarios predicted CO₂ production about right.
B) Model scenarios overestimated CO₂ production.
C) Observed CO₂ production has exceeded the worst model scenarios.
D) Observed CO₂ production rose but has recently declined below IPCC model scenarios.
E) CO₂ production matches the middle range of model scenarios.