The Earth contains a great diversity of species. This:
a. will make no difference in the survival of life if there were major changes in the environment.
b. decreases the chance that at least some organisms will be able to survive major changes in the environment thereby ending life.

The correct option is A) will make no difference in the survival of life if there were major changes in the environment.

Explanation:

Due to genetic diversity, variations in species are caused which makes some organisms of a species to be better adapted than other members of the species. These variations cause organisms to survive when differences in the environment occur. Although the allele frequencies might change due to the changes in the environment but the phenomenon of genetic diversity allows life to sustain on earth even when conditions will become unfavourable.  

i think the answer is b.