Help! Which is evidence that scientists use to support the big bang theory? A. Most galaxies are moving away from each other. B. The outer planets are mostly composed of hydrogen and helium. C. Most orbits have an elliptical shape. D. Earth is the only planet with permanent liquid water on its surface.

Real scientists do not 'use' evidence to support a theory.  Real scientists offer theories to explain what they observe.  The so-called "Big Bang Theory" is the most useful explanation offered so far to explain the observed fact that most galaxies are moving away from us, and the farther from us a galaxy already is, the faster it's moving away.