the correct answer is A- Reproductive isolation occurred through behavioral isolation
A process of formation of a new species from an existing species is called speciation. New species may formed due to geographical or reproductive barriers which isolates the members of a population of a species to form a new species.
In the given question, speciation in In the leopard frogs occurred due to a particular or specific call given by males to the females. The courtship call lead to reproductive isolation due to change in behavior. Such type of behavioral change will help in recognizing mates of the same species and this will act as a reproductive barrier among the other related species.
So that it can protect exposed tissue, a layer of meristematic cells, cork cambium, or phellogen rises from the cortex.
Open-mindedness is needed for the emerging scientific ideas to be accepted (or : to not be rejected without consideration).
Additionally, open-mindedness as a attitude often leads to new scientific ideas emerging: it means that people are more comfortable to try out new things and to test new hypotheses.
I think the most accepted Theory to make up living things is the cell theory.