Question

Different environments cause different species to __________.

Answer 1

I think the best answer is become more diverse since different environments require different adaptations which will lead to further diversity.  I am interpreting the question as if you have different species all in different environments. 
I hope this helps and let me know if I interpreted the question incorrectly in the comments so that I can fix it.

Answer 2

Your answer is definitely A. Become more diverse.