They are thought to have separate paths of evolutionary development.
They developed along different evolutionary paths.
They had independent evolutionary development.
The answer is C. My explanation is that in the sentence, it has the words “will probably,” next to each other, so that means it is not a fact and it is not a 100% for certain that it will/had happen(ed). People may have different feelings/views about it. Also, all of the other sentences are more direct and do not have those words, and they sounds confident. Hope this helps!