Biologically: Nitrogen gas (N2) diffuses into the soil from the atmosphere, and species of bacteria convert this nitrogen to ammonium ions (NH4+), which can be used by plants. Legumes (such as clover and lupins) are often grown by farmers because they have nodules on their roots that contain nitrogen-fixing bacteria. (Learn more about this process in the article The role of clover.)
Through lightning: Lightning converts atmospheric nitrogen into ammonia and nitrate (NO3) that enter soil with rainfall.
Industrially: People have learned how to convert nitrogen gas to ammonia (NH3-) and nitrogen-rich fertilisers to supplement the amount of nitrogen fixed naturally.
The best answer to the question that is being given above would be letter A. The most complex level of organization hierarchy that climate change could potentially affect is Earth's Biosphere - which holds every living thing in the planet. This climate change will destroy it more destruction to Mother Nature occurs.
Diversity and emergence of new traits (can be beneficial in some cases). Mutations are part of what drive evolution and allow for that change to take place.