Based on the observed red shifts in the spectral lines of distant galaxies, astronomers conclude that the universe is expanding earth is in the center of the universe the universe is in a steady state the universe is contracting

Option (1)

Explanation:

Redshift is usually defined as the shifting of the beam of light of any astronomical body (object) towards the longer wavelength. This means the shifting of light towards the red coloured end.

The astronomers often determine the movement of objects with respect to a fixed point by using the Doppler shift, where its frequency gets shifted depending upon the motion of the light.

After much of the research and analysis, it has been observed by the astronomers that the light emitted from the distant bodies within the universe is redshifted, i.e. the light frequency is moving towards the red colour. This signifies that all the galaxies are retreating from us, depicting that the universe is continuously expanding.

Thus, the correct answer is option (1).