【单选题】

Since the Hawaiian Islands have never been connected to other landmasses, the great variety of plants in Hawaii must be a result of the long-distance dispersal of seeds, a process that requires both a method of transport and an equivalence between the ecology of the source area and that of the recipient are

A、
There is some dispute about the method of transport involveD、Some biologists argue that ocean and air currents are responsible for the transport of plant seeds to Hawaii. Yet the results of flotation experiments and the low temperatures of air currents cast doubt on these hypotheses. More probable is bird transport, either externally, by accidental attachment of the seeds to feathers, or internally, by the swallowing of fruit and subsequent excretion of the seeds. While it is likely that fewer varieties of plant seeds have reached Hawaii externally than internally, more varieties are known to be adapted to external than to internal transport.
It can be inferred from information in the passage that the existence in alpine regions of Hawaii of a plant species that also grows in the southwestern United States would justify which of the following conclusions
A、The ecology of the southwestern United States is similar in important respects to the ecology of alpine regions of Hawaii.
B．There are ocean currents that flow from the southwestern United States to Hawaii.
C．The plant species discovered in Hawaii must have traveled from the southwestern United States only very recently.
D．The plant species discovered in Hawaii reached there by attaching to the feathers of birds migrating from the southwestern United States.