Answer:
D. the computer model of the greenhouse effect must be incorrect in some respect
Step-by-step explanation:
According to the scientists, carbon dioxide is playing a major role in green house effect. Increasing carbon dioxide level in the atmosphere is also leading to an increase in global warming. To predict this situation, a computer model of greenhouse effect is also created. It aims at predicting the warming level based on some simulations.
However the model's prediction does not match with real life observations. It predicts the warming to be lot more than observed in reality. This error can be a result of some technical issue in the computer model. Also, real life observations are based on many factors and the given computer model is based just on the level of carbon dioxide in atmosphere. So it might have calculated incorrect warming level.