I mean the nervous system is the one that feels the pain so...
Answer:
The conditions of the early Earth were not at all feasible for the survival of life. The primitive conditions of the earth had a very heated environment. There was not enough amount of free oxygen present. The only oxygen that was found at that time was in the water molecules of in other molecules and hence there was no free oxygen. Some prokaryotes, which were able to survive in hydrothermal vents were able to survive in these primitive conditions.
Answer:
d is the right answer to your question
