To which are crows in the passage compared in the use of tools?

* Hướng dẫn giải

Dẫn chứng: Scientists have found that rooks - a member of the crow family - were able to figure out how to raise the water level in a laboratory container by dropping stones inside to retrieve a tasty worm floating on the surface.

The only other animal shown to be able to perform the same task is the orang-utan, which was able to grasp a floating peanut by spitting water into a tube.