Which statement is true about natural selection and evolution?

a. evolution is the mechanism by which natural selection occurs.

b. natural selection and evolution both show change over time.

c. evolution and natural selection occur separately in an ecosystem.

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.

Tropic of cancer and tropic of capricorn

The first immigrants to settle in what is now the united states were the ancient ancestors of modern native americans. the precise routes of those first north american immigrants are disputed, but there is no uncertainty about the fact that every human being on the continent is either a recent immigrant or a descendant of earlier immigrants. since the first immigrants came here from asia more than thirteen thousand years ago, there have been four large and easily recognizable modern waves of immigrants into the united states.