Which statement is true about the elements of the earth?
a.
earth's elements are used and reused in different molecules over time.
b.
earth's elements stay in the same areas of the lithosphere, hydrosphere, or atmosphere where they originated when the earth was formed.
c.
earth's elements pollute the environment and should be discarded.
d.
earth's elements are constantly being created and destroyed so that a constant amount of matter exists.