What are the pros and cons of population growth ?

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

Explain how earths tilt and revolution around the sun affects weather and climate

Identify the youngest layer in the figure ( have to click one letter)