Question

question 10
what observational evidence supports the fact that our universe is expanding?
detection of cosmic strings
redshifts of galaxies
discovery of quasars
discovery of black holes
evolution of galaxies with distance

Explanation:

Redshifts of galaxies are the key observational evidence for cosmic expansion. Edwin Hubble observed that most galaxies show a redshift (shift of light to longer wavelengths), and the redshift increases with the galaxy's distance—consistent with the universe expanding. Other options (cosmic strings, quasars, black holes, galaxy evolution) do not directly support expansion.

Answer:

Redshifts of Galaxies