20 which of the following was likely present in earth's early atmosphere over four billion years ago?
a. abundance of oxygen
b. very cold temperatures
c. presence of inorganic molecules
d. low levels of ultraviolet radiation

C. Presence of inorganic molecules

Explanation:

At that point, there is no life found on Earth. The Great Bombardment is about to happen around this time, and the Great BOmbardment is what opens the gate of life. Until then, there were many inorganic molecules.

C. Presence of inorganic molecules

Explanation:

As it says in the lessons it says that there was a lack of oxygen, extremely hot temperatures, because of the lack of atmosphere in the air so Earth was bombarded by ultraviolet radiation and everything else from the sun that the atmosphere protects us from today. There were tons of ultraviolet radiation due to the fact that our atmosphere isn't what it today so therefore it must be C. Presence of inorganic molecules because, no human or animal, plant could live on the planet in Early Earth time.

d.

explanation: