Nitrogen Fixation: Root and Bacteria Interactions. Nitrogen is an important macronutrient because it is part of nucleic acids and proteins. ... The most important source of BNF is the symbiotic interaction between soil bacteria and legume plants, including many crops important to humans.
C is the most likely answer to this question.
It is important to understand because it's the way all cells reproduce (except sperm and egg cells, they do meiosis), and our cells are the essential parts of our whole being.
