Why is earth's current atmosphere made up mostly of nitrogen and oxygen?
a. earth is eroding.
b. earth is warming up.
c. earth is continuing to cool.
d. earth has living things on the surface.

i don't get what you mean

explanation:

the answer is c     : )

explanation:

i don't have an explanation because i don't know, but i think the answer is c because i googled it and google is right : ) just kidding google isn't allways right but the answer is still c. i hope this !

d. hip hop

it was originated in the 70s while the harlem renaissance occured in the 1920s