TOEFL Reading: ETS-TOEFL阅读机经 - 3_3FQIX8IUY1U4VTL$

In paragraph 2, why does the author discuss pollination A. To provide evidence that in many tropical tree species flowering is at least somewhat predictable B. To help explain why flowers on trees in tropical rainforests can be absent most of the time C. To help explain why different trees of the same species bloom at the same time D. To suggest one reason why trees might benefit from adjusting their flowering to the rains