GRE Reading Comprehension: ETS Official Practice 150-GRE OP150: 阅读 - M73_4594SO51LC7YZ

Which of the following, if true, would be additional evidence to suggest that hummingbirds are attracted to the red flowers and hawkmoths to the white flowers of the scarlet gilia? A. Uncovered scarlet gilia flowers, whether red or white, became pollinated at approximately equal rates. B. Some red flowers of the scarlet gilia that remained uncovered at all times never became pollinated. C. White flowers of the scarlet gilia that were covered at night became pollinated with greater frequency than white flowers of the scarlet gilia that were left uncovered. D. Scarlet gilia plants with red flowers covered by day and scarlet gilia plants with white flowers covered at night remained unpollinated. E. In late August, when most of the hummingbirds had migrated but hawkmoths were still plentiful, red scarlet gilia plants produced fruit more frequently than they had earlier in the season.