The answer is A: They produce pollutants that harm people.
Hope this helps
<span>The correct answer to this question is the following:
The crust’s role in biogeochemical cycles allows it to provide the raw materials necessary for life on earth. The crust actually affects earth in a massive variety of ways, that are impossible for us to understand without the research undertaken by scientists to understand more about its' effects on life.</span>
B. Is characterized by four different zones.
Explanation:
Homologous chromosomes are 2 physically different chromosomes that have the same genes but are not genetically identical. Sister chromatids are 2 copies of a single chromosome and so are genetically identical (they also are physically attached to one another).
