Question

13 the main evidence to support an expanding universe originates from the idea that
a all the distant galaxies are moving away from earth.
b all the distant galaxies are moving toward earth.
c wavelengths do not change.
d distant galaxies must have originated far apart from each other.

Explanation:

The evidence for an expanding universe comes from the observation that distant galaxies are moving away from Earth (Hubble's law). This is shown by the redshift of their light. Option B is incorrect as galaxies are moving away, not towards. Option C is wrong as wavelengths do change (redshift). Option D is not the main evidence. The key is the motion of galaxies away from Earth.

Answer:

A. all the distant galaxies are moving away from Earth.