Question

Select the correct answer from each drop-down menu :

Compared to modern Earth, Precambrian Earth's atmosphere and oceans were much richer in ________
because it was so prevalent in
_________ .

A. carbon dioxide, oxygen, salt

B. volcanic gas, single-called organisms, crustal rock

Answer 1

a

Step-by-step explanation:

you got to think single cell organisms were not abundant however the Co2 and salt compounds were as well as the oxygen needed to help evolve them which led the moncellular creatures to evolve into algae and fungi and then those 2 formed a symbiotic relationship to form lichen

Answer 2

First one is carbon dioxide, second one is volcanic gas.

Step-by-step explanation:

I got it right on edmentum.