Answer:
they created oxygen for living species
Subsoil: This layer has normally less organic matter than the A horizon, so its colour is mainly derived from iron oxides. Iron oxides and clay minerals accumulate as a result of weathering. In a soil, where substances move down from the topsoil, this is the layer, where they accumulate.
Note: This information has been taken out of a website.
In terms of individual states, the answer would be New Jersey. Otherwise, the REGION that is most densely populated is the east coast, specifically the Northeastern part of the U.S.
Hope this helps!
B. Natural selection and Evolution both show the change over time in the survival of a specific organism. Natural Selection chooses traits that correspond the best with the ecosystem, while evolution gradually changes the species as a whole to cope with the surroundings.
