Large amounts of oxygen gas appeared in Earth's atmosphere about ________ years ago.
A)200 million
B)1)7 billion
C)2)7 billion
D)4)5 billion

Question

Quizplus · Accepted Answer

This is commonly referred to as the Great Oxygenation Event, in which photosynthetic organisms began to produce oxygen as a byproduct and gradually built up oxygen levels in the atmosphere. This event occurred around 2.7 billion years ago. Options A, B, and D are not accurate as they do not align with the known timeline of Earth's history.

Large Amounts of Oxygen Gas Appeared in Earth's Atmosphere About