During the Precambrian time, the oceans and atmosphere formed around Earth, and the concentration of oxygen gas eventually reached the point where it could support aerobic .

Plz plz plz quick! 49 points for whoever which of the following statements about greenhouse effect is true? *life on earth is suffering because of greenhouse effect *the greenhouse effect is caused by human activity *all greenhouse gases are harmful *life on earth would not exist without the greenhouse effect

15 ! come and answer! a(n) is the general term for an infectious disease that has spread across a city, region, or country.

Which of the following words best matches this definition: the process in which the best adapted organisms survive and pass on their traits, while those that are not well adapted do not survive to pass on their traits. question 3 options: acquired selection natural selection artificial selection organic selection