Question

1. the event that released oxygen in earths early atmosphere happened around __________ years ago. 2 billion 4.6 billion 3.2 billion 10 billion clear all

Explanation:

The Great Oxygenation Event, which released oxygen into Earth's early atmosphere, occurred around 2.4 - 2.3 billion years ago. Among the given options, 2 billion years ago is the closest estimate.

Answer:

A. 2 billion