GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - DP25547BR4LFJKW5J

Which of the following most logically completes the passage above? A. in the desert climates where cactuses grow, carbon dioxide is significantly more abundant in the air during the day than at night. B. cactuses that have quintral plants growing as parasites on them do not absorb as much carbon dioxide from the air as do cactuses of comparable size that are free of parasites. C. quintral plants are the only kind of parasites that grow on such kinds of cactuses. D. in areas where quintral plants are common, individual cactuses often have several such plants. E. nearly all of the carbon dioxide absorbed from the air by quintral plants is absorbed during the day.