Which of the following is evidence that supports the big bang theory?
A. Light from other galaxies sometimes takes thousands of years to
reach Earth, which shows that the galaxies are moving away from
Earth.
B. Light from other galaxies shows that light elements formed before
heavier elements.
C. Light from other galaxies always travels at the same speed, which
shows that the galaxies are moving away from Earth.
D. Light from other galaxies appears shifted toward the red end of
the spectrum, which shows that the galaxies are moving away
from Earth