Which one of the following statements is TRUE for Earth?
A) The oxygen in our atmosphere was created by evaporation of seawater,allowing life to move from the seas onto dry land.
B) Earth has always had an oxygen-rich atmosphere,which was one reason life could develop.
C) Outgassing by volcanic eruptions converted the carbon-dioxide-rich atmosphere into an oxygen-rich atmosphere,thus creating conditions in which life could develop.
D) Life developed in a carbon-dioxide-rich atmosphere,and life helped convert this into an oxygen-rich atmosphere.

Question

Quizplus · Accepted Answer

There is evidence that early Earth had a carbon-dioxide-rich atmosphere, and that the first organisms, such as cyanobacteria, were able to photosynthesize and produce oxygen as a byproduct. Over time, this led to an increase in atmospheric oxygen levels, eventually providing the conditions for more complex life forms to evolve. Therefore, option D is correct. Option A is incorrect because while evaporation of seawater can contribute to atmospheric oxygen levels, it is not the primary source. Option B is incorrect because early Earth did not have an oxygen-rich atmosphere. Option C is also incorrect because volcanic outgassing is thought to have contributed to the early atmosphere, but did not directly create an oxygen-rich atmosphere.

Which One of the Following Statements Is TRUE for Earth