Which best explains a primary reason for the inability of life to exist in Earth's early atmosphere?

Consider the chemical environment of the early atmosphere: The early atmosphere was reducing, meaning it favored the formation of simple organic molecules but lacked the stability and energy systems needed for complex life forms to thrive. This contrasts with the current oxidizing atmosphere, which supports diverse life forms.

Evaluate the incorrect options: The presence of abundant ozone blocking ultraviolet radiation is incorrect because ozone (O₃) forms only in the presence of oxygen, which was scarce in the early atmosphere. The claim that the atmosphere was composed mainly of nitrogen and oxygen is also incorrect, as these gases became dominant much later. The idea that the early atmosphere was too cold for chemical reactions is incorrect because chemical reactions did occur, leading to the formation of simple organic molecules.