the answer is a wheel
do away with
in complete agreement
separate; break free
starting a new position with a formal ceremony.
people who wanted the north to cooperate with the south
to give up
perform a service for free
involuntary service in military
withdraw; move away from enemy
expert who gives advice
Reciprocal altruism: In evolutionary biology, the term reciprocal altruism is defined as a particular behavior in which a specific organism acts in a certain manner or way that leads to temporary reduction of its fitness, therefore, increases the other organism's fitness and holding an expectation that the other organism will act or behave the same way in future. It can happen between individuals who are non-relative.
In the question above, the given concept is called reciprocal altruism.