The carbon and hydrologic cycles?
send all matter into the solid earth to stay forever
have no beginning and no end; they just go on and on
operate in complete isolation to the physical systems of the earth
have been discontinued because of lack of interest in them by high school students

Have no beginning and no end; they just go on and on

Although this may be the opposite of what you think i will say it anyway. you were brought into this world for a reason and you still have soo much ahead of you. not everybody has an opportunity of living a great life, but it doesn’t give you a reason to end everything. somebody in the world loves you, and imagine what you would do to them if you left forever.