GRE Reading Comprehension: Princeton-GRE阅读Princeton - OJ1C72F489HKR6_6C$

Which of the following can be inferred about the spread of ragweed pollen? A. Ragweed plants adapted to desert and mountain climes tend to spread fewer grains of pollen than do plants in other locations. B. Some attempts to control it may exacerbate the problem. C. The clumping of pollen grains caused by high humidity levels affects the ability of the wind to carry the grains.