The dataset CO2 contains the results of an experiment on the cold tolerance of a grass species, Echinochloa crus-galli. There are several variables in this dataset, but we are interested in two in particular: the Treatment which denotes if the plant was chilled or not and uptake which is a numeric variable denoting the uptake rate in umol/m2sec. Construct a 95% confidence interval for the difference in means between uptake rate between plants that were chilled and plants that were not chilled.