Answer:
reason for studying human genetics is that it gives us a powerful tool for understanding and describing human evolution. At one time, data from physical anthropology (including information about skin color, body build, and facial traits) were the only source of information available to scholars interested in tracing human evolutionary history. Today, however, researchers have a wealth of genetic data, including molecular data, to call upon in their work.
Answer: A niche is the role an organism plays in the ecosystem.
Explanation: A niche also determines how the organism interacts with other organisms in an ecosystem
I am going with x-rays; it is the most visible to the naked eye out of all the choices.