Q: What important and unusual physical property (for birds) do ostriches and penguins share?


Read this paragraph and choose the correct option from the provided answers:

There are about 10,000 living species of birds. Almost all of them can fly. Flying birds are classified in 29 orders. Most species belong to the order of perching birds. A few birds are flightless, such as the ostrich and penguin, but they evolved from a flying ancestor.

 Choices:

- waterproofness

- webbed feet

- bonelessness

- flightlessness


A:
flightlessness