Edwin Hubble calculated the expansion rate of the universe. On what evidence did he base his calculation?
\l "\l " A. Levels of background radiation
\l "\l " B. Differences in redshift for galaxies
\l "\l " C. The existence of planets outside of our solar system
\l "\l " D. Levels of helium in the universe
\l "\l " A. Levels of background radiation
\l "\l " B. Differences in redshift for galaxies
\l "\l " C. The existence of planets outside of our solar system
\l "\l " D. Levels of helium in the universe