TOEFL Reading: ETS-TOEFL阅读机经 - 7JI13M7U6KEN8M3HL$

In paragraph 1, the author compares pollen moved by wind with letters thrown off roofs in order to A. explain why there are relatively few species of trees that depend on wind pollination B. compare natural, biological processes with human social practices C. make a point about the probability of wind-blown pollen reaching a tree of the same species D. argue against the common assumption that the tallest trees are the most likely to employ wind pollination