Answer:
D
Explanation:
D is the only option where the cause of the pollution is not something man-made.
A variation is a reference to the differences or deviations, such as the structure and form, as for crossing over is the exchange of genetic material between the non-sister chromatids of the homologous chromosomes during meiosis.
Krypton helps geologist determine the absolute age of a rock
it involves negative feedback loop
Explanation:
the loop allows living organisms to maintain homeostasis
