<u>Answer</u>: Option 3 Coevolution
<u>Explanation</u>:
<em>Coevolution</em> is a process in which two individuals reciprocally affect each other's evolution. In this process the interacting species exert selective pressures on each other thus, affecting their evolution. Due to this reciprocal adaption they become so close that the evolution of one species is affected by the other.
That would be an isotonic solution
Just look it up on the internet