I believe the answer is retrovirus
Substitution I believe is the right answer but I never learned identity property
Pollution in the TROPOSPHERE will have the greatest effect on human health.
The troposphere is the lowest level and humans also live on the lowest level. Therefore, pollution in the troposphere will have the greatest effect on human health.
Answer: D. strata
Explanation:
I took a small quiz and it had this same question on it and the answer was strata
Hope this helps :)