Help! All incorrect or nonsense answer will sadly be reported and blocked. Thanks for your time and help :-P

What causes the cyclical changes in the appearance of the moon?

In the figure, polygon abcd is transformed to create polygon a′b′c′d′. this transformation is a by a factor of .

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