Question

what evidence supports the idea that the universe is expanding? stars are getting cooler over time dark matter is pulling galaxies inward redshift shows galaxies are moving away from us question 2 what does the cosmic microwave background radiation (cmb) tell scientists? it is leftover energy from the big bang it shows that fusion only occurs in stars it is the reason galaxies cluster together question 3

Explanation:

Question 1:

To determine the evidence for the universe's expansion, we analyze each option:

• Stars cooling over time is about stellar evolution, not universe expansion.
• Dark matter pulling galaxies inward would suggest contraction, not expansion.
• Redshift (Doppler effect for light) shows galaxies’ spectral lines shift to longer wavelengths, indicating they move away from us, supporting cosmic expansion.

To find what CMB tells scientists, we analyze each option:

• CMB is a faint radiation filling the universe, considered leftover thermal energy from the Big Bang (when the universe was hot and dense).
• Fusion in stars is unrelated to CMB’s origin.
• Galaxies cluster due to gravity/dark matter, not CMB.

Answer:

C. Redshift shows galaxies are moving away from us

Question 2: