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