Question

Different environments cause different species to __________.

A)become more diverse
B) become less diverse
C)become extinct
D)have similar traits

Answer 1

Your answer is definitely A. Become more diverse.  

Answer 2

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.