What is the ultimate cycle? describe it and all its interactions

Answer the use of flood plains and irrigation;

Answer is b)eutrophication occurs when excess nutrients are present in aquatic ecosystems, resulting in the increased production of plant life and the subsequent decrease in the oxygen levels of the watereutrophication occurs when there are excess nutrients in a body of water. this results in plants having more food and reproducing  more, sometimes leading to more aquatic animal life as well. ultimately, this can reduce the oxygen level in the ecosystem. 

Global warming is happening at an alarming that there is no way of preventing it from happening because humans contribute to it