Which of the following best explains why the night sky is dark?

Which of the following best explains why the night sky is dark?

a) The universe has not always looked the way it looks today.

b) The universe is not infinite in space.

c) The distribution of matter in the universe is not uniform on very large scales.

Answer: b) The universe is not infinite in space.

As the space of the universe is not vast without limits, the sky at night seems dark. If the universe is infinite and the stars are also infinite distributed evenly in space then every direction in space that is observed will become bright as there will be stars in the direction of observation. On the contrary, experiences and various invulnerable theories have come up with results showing that the universe is actually a limited age and size with limited stars. The light from farther galaxies has not had enough time to get to us due to the impulse of relativity and the limited age of the whole universe. Moreover, the expansion of the universe makes the light coming from distant galaxies to be red-shifted thus making the sky at night appear darker.