The diagram represents the Moon and its orbit around Earth. The arrow labeled X represents the force that keeps the Moon in its
orbit.
Which force is represented by X?
a. gravity
b. electricity
c. friction
d. magnetism

Which revelation resulted from the observation of the spectrum of different galaxies? a. there were more galaxies whose spectrum was blueshifted b. there were no galaxies whose spectrum was redshifted c. there were more galaxies whose spectrum was redshifted d. there were no galaxies whose spectrum was blueshifted