Question

there is a theory that gravity could pull galaxies back together, causing a reverse big bang. which observation makes this theory less likely than the idea that the universe may continue to expand? background radiation is present. galaxies exist outside of the milky way. the expansion of the universe is accelerating. gas giants form farther from the sun, where temperatures are cooler.

Explanation:

The accelerating expansion of the universe suggests that the forces driving expansion are overpowering gravity's pull, making a reverse big - bang less likely. Background radiation is evidence for the Big Bang but not relevant to the likelihood of a reverse big - bang. Galaxies outside the Milky Way is a general fact about the universe structure. The formation of gas giants is related to solar - system formation, not the overall universe's expansion or contraction.

Answer:

C. The expansion of the universe is accelerating.