Why doesn't the level of oxygen in the atmosphere decreases'?

What are 3 reasons that natural selection occurs

Which of the following statements is a scientific claim? a. the early solar system had large amounts of water; so, the oldest objects in the solar system should also be abundant in water. b. earth is shaped like a sphere even if not all of the scientific observations related to its shape support this idea. c. the mass of the universe is much greater than current models predict; it is not possible to explain this inconsistency. d. planet earth is abundant in water, but there is no way to scientifically determine from where earth's water originated.

White-headed woodpeckers are adapted to have strong beaks that can break into tree trunks to find bugs and can also open pine cones to get at the seeds. white-headed woodpeckers are best adapted to living in the biome.