I believe the answer may be commensalism. This is a relationship between two organisms where one of the organism benefits from the relationship, but the other is neither harmed nor helped.
Answer:
The control group? (IDK)
Explanation: Isn't the control group the group that has all the factors that the experimental group has, except for the factor that's being changed?
The first one cause many different animals can be vertebrates
The formation of the first cells is common in both hypotheses.
