The sentence that best explains the primary reason for the inability of life to exist in Earth’s early atmosphere is include option C: " Volcanic eruptions and comet collisions added different gases to the atmosphere".
There are lot of gases being released into the atmosphere due to Volcanic eruptions that effect a severe lack of oxygen situations and automatically life on Earth was almost unsustainable.
During the early years of the Earth volcanic eruptions were much more common than they are today. When these volcanoes erupted, they spewed many gases into the atmosphere, including: Carbon dioxide and Nitrogen.
Therefore, correct option is C.
Learn more about Volcanic eruptions, refer to the link:
https://brainly.com/question/1622004