Thr answer is D. Minerals
Melanin. “Melanin is produced within the skin in cells called melanocytes and it is the main determinant of the skin color of darker-skinned humans. The skin color of people with light skin is determined mainly by the bluish-white connective tissue under the dermis and by the hemoglobin circulating in the veins of the dermis.” -Wikipedia
Most nitrogen fixation is performed by bacteria, but they are biotic, not abiotic. Lightning does have the ability to fix atmospheric nitrogen.
Natural Factors:
Ocean Currents, Distance of the Sea, Wind Directions, Topography, Your country's distance from the equator , Volcanic Eruptions, The sun, and especially humans.
The ultimate purpose of life is to reproduce and pass on the genes to the offspring.
