Early in the earth's history there was little to no oxygen into atmosphere. how did oxygen levels in the atmosphere reach current levels?

a) volcanoes released oxygen from within the earth.

b) the earth captured oxygen from space with its gravity.

c) water molecules on the earth were broken to release oxygen.
eliminate

d) early bacteria and plants released oxygen through photosynthesis.

Give three differences between oceanic and continental crust brainliest will be awarded

Pls pls pls choose a city in ecuador, peru, or bolivia. look up all the information you can find about it. then write about the city of your choice in a report of 150 words. after you have finished your writing assignment, review it and correct any errors you find in punctuation, grammar, spelling, and the way you write your sentences. can you choose words with more exact meanings or more vivid descriptions?

Which of the following is the unit of measurement used to describe the severity of an earth quake? velocity, magnitude, volume, density.