Question

What was the "oxygen revolution," which took place 2.3 billion years ago?

Answer 1

Answer:

Option-C

Explanation:

The oxygen revolution refers to the increasing concentration of oxygen in the atmosphere around 2.3-2.4 billion years ago.

The studies have suggested that before the oxygen revolution the Earth's atmosphere was full of the hydrogen sulfide and methane gas in which the anoxygenic prokaryotes were evolving.  

The cyanobacteria and other photosynthetic bacteria evolved the photosynthetic pigments which performed the experiment and oxygen gas was produced as a by-product.

With time this oxygen got accumulated in the atmosphere and the oceans and became one of the factors of anaerobic prokaryotic, the condition which they cannot escape. Later the oxygen producing prokaryotes evolved and formed the first eukaryotes.

Thus, the selected option is the correct answer.