Beavers, by damming streams, create wetland habitats that support diverse plant and animal communities. Once nearly trapped to extinction in North America, beaver populations have rebounded, and ecologists now study them as a model "ecosystem engineer." Reintroducing beavers to degraded watersheds, some studies suggest, can restore wetlands more cheaply and effectively than human engineering.
Which choice best states the main idea of the text?
- A
Beaver populations are now stable.
- B
Beavers were nearly trapped to extinction in North America.
- C
Human engineering is always less effective than animal engineering.
- Dcheck_circle
Beavers function as ecosystem engineers and may aid wetland restoration.
Explanation
The passage centers on beavers as ecosystem engineers and their restoration potential — B. A is a supporting fact; C overstates; D is not the focus.