Question

in the 1920s, edwin hubble looked at the spectra of stars from distant galaxies. to his surprise, he found that all of these spectra were red - shifted, and that the more distant the galaxy, the greater the red - shift. what is a reasonable conclusion from this evidence?
the universe is expanding.
the universe is contracting.
the universe is unchanging.
the universe is curved.

Explanation:

Edwin Hubble's discovery of greater red - shift in more distant galaxies supports the idea of an expanding universe. Red - shift indicates objects are moving away.

Answer:

The universe is expanding.