What formed the great rift valley? A. Volcanic activity and tectonic movement

B. A massive earthquake 200 years ago

C. A Mountain range west of the valley

D. A massive basin in the valley center

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