Suppose that species a evolves and species b evolves in response to the changes in species a. species a then changes in response to the changes in species b. this is an example of a. coevolution. b. extinction. c. convergent evolution. d. adaptive radiation.

This kind of evolution where both species are evolving in response to one another is called coevolution.

Answer : Option A coevolution

Explanation :

Coevolution is the form of evolution in which the evolution of one species reciprocally affects the evolution of the other species, in simpler terms we can say that is a type of evolution in which one species' evolution is dependent on the other.Extinction is the process where a particular species cease to exist.Convergent evolution is the type of coevolution in which two species which are not related to each other evolve to adapt similar traits as they live in similar ecological niches.Adaptive radiation is a process in which a species rapidly diversifies into different types and occupies newer areas.

Based on all these definition it is clear that according to the question, the case is of coevolution.